Holiday Homework -...

Holiday Homework Class: VIII (Intl), Subject: BGS

Questions for 2&3 marks:

Chapter 8:

1. What is green house?

2. What is global warming?

3. What are called green house gas?

4. How deforestation is causing global warming?

5. Define disaster.

6. What are the kinds of disaster? Define them.

7. What is Tsunami?

8. What is land slide?

9. What is wild fire?

10. How the geographical position of Bangladesh is causing natural disasters here?

Chapter 9:

11. What is meant by population policy?

12. What do you understand by community based family planning programme?

13. What is the role of women’s participation income generating activities?

14. What are the plans of government for the expansion of women education?

15. What is the objective of population policy?

Chapter 10: 1. What is juvenile delinquency?

2. Which vices are treated as juvenile offence?

3. How poverty is the main reason of juvenile offence in our country?

4. How socio economic programme can prevent juvenile offence in Bangladesh?

5. What is drug addiction?

6. Do you agree that the influence of bad culture is another main reason of drug

addiction? How?

CHAPTER 11:

Why Bangladesh is called the country of multi-cultures?

How the ethnic minority groups has enriched the economy of our country?

Living place, religious life, economic life of the ethnic minority groups.

For example-

Briefly discuss the religious life of the Saontals.

Chapter 12 1. Write down the name of the natural resources found in Bangladesh?

2. Write down the name of 4 mine resources found in Bangladesh.

3. How does natural resources help in production and creating employment?

4. What is the importance of the largest export oriented industry in Bangladesh?

5. Why drug industry is considered as the most prospective industry in Bangladesh?

Questions for 6 marks:

Chapter 8: 1. Describe the causes and effects of global warming.

2. Analyse the causes of natural disasters of Bangladesh.

3. Analyze the impact of natural disasters on the life and economy of Bangladesh.

4. What can be the causes of earthquake? Explain.

5. How drought can be prevented? Discuss.

6. What can be done to prevent the loss of river erosion? Explain.

7. Explain the causes of river erosion.

8. What can be your actions as the part of post-disaster activities?

Chapter 9:

1. What are the objectives of the population policy of Bangladesh? Explain.

2. How population can hinder the overall development of Bangladesh? Explain.

3. Describe the ways to turn population into human resource.

Chapter 10:

1. What are the causes that make the juvenile offenders?

2. What are the steps that can be taken to prevent juvenile offence?

3. What are the causes that make the juveniles drug addict?

4. What are the effects of drug addiction on the family of the addict?

5. How can you contribute in the society by taking steps to prevent drug

addiction in our society?

Chapter 11

The social life and cultural life of the ethnic minority groups

For example-

What has made the Garo society different from other minority groups

Chapter 12

1. What is the real situation of bio-diversity in Bangladesh?

2. What is the contribution of industry in socio-economic development ?

For 1 mark answer , MCQ, T/F,F/B and figures - diagrams students have to read

the book properly

1. Look at the diagram of DNA and RNA: answer the question below-----

a) Level the following diagrams A to F?

b) Write the differences between DNA and RNA?

iii) What is nucleotide? Draw a nucleotide chemical structure.

b) Who are the inventors of DNA double helix molecular structure model ?

c) Write the differences between mitosis and meiosis cell division? 2

2. The diagram shows the cross between yellow and green colour hens. The Punnett grids

(squares) for predicting the outcomes of first filial generation.

a) Fill up the punnett squares with phenotypic and genotypic ratios.

b) Define the terms 5

Test cross, back cross, homozygous allele, dominant allele and co-dominant allele

c) Work out what kind of off-spring would be produced if a homozygous yellow colour hen

mated with one which was homozygous green colour?

d) How many pairs and types of chromosomes present in human?

3. Complete the tables:

Terms Definition and function

a) Purines

i)

ii)

b) Pyrimidine i)

ii)

c) gene i)

d) Mitosis i)

ii)

e) Meiosis i)

ii)

4. Complete the table about of inherited diseases:

Terms Causes and effects

a) Mutation

b) Cystic fibrosis

c) Sickle cell anaemia

d) Huntington’s

disease

e) Co-dominant

Holiday Homework Class: VIII (Intl), Subject: English Language

1. Argumentative Essay

(a) ‘Parents Should Monitor Their Children’s Internet Use’ To what extent do you agree with this statement.

(b) ‘Children under fifteen should not be given pocket money.’ To what extent do you agree with this statement.

© ‘There is no place like home’ Do you agree with this view. (d) ‘Parents should not burden children with their own dream’. Do you agree with this view. (e) ‘Travel broadens the mind’. To what extent do you agree with this view. (f) ‘The best gift that anyone can get is a book’ Do you agree with this view.

2.Descriptive Essay:

(a) Describe a person who has been a big influence on your life. (b) Describe a journey you enjoyed (c) Describe the qualities you look for in a friend

3.Narrative Essay:

(a)The most challenging thing I have ever done

(b) The Day I Decided to Change My Life

©My Father’s Influence on Me

4.Letter Writing:

(a) You are Mr.John/ Ms.Joan, you are the librarian of ABC International School. You have ordered

some specific books from Bookworm Store. But the books were not supplied to you. Write a letter to

the sales manager to deliver the books immediately

(b)You bought a Laptop one week ago from Electronic Zone. But it is not charging properly and you

suspect there is a manufacturing defect in the product. Write a letter to the sales manager asking him

for an immediate replacement since your laptop is still within the warranty period. You could quote

the bill number and the date of purchase as reference.

(c) You are Mr.John/ Ms.Joan, you went to a renowned jewellery shop, City Jewellers to buy a diamond

ring. A salesman in that shop misbehaved with you . Write a letter to the manager of the store to report

the incident and request him to take necessary action.

5.Report Writing:

(a) You are the reporter of Bangladesh Observer. Five people died in a terrible car and bus collusion at

Dhanmondi. You are given the duty to investigate the incident. Write a news report about it.

(b)You are the reporter of The Daily Star. The students of Bangladesh International School and College

have started a literacy campaign to teach the street children near Mohakhali and Cantonment area.

They are urging the other English Medium schools to do the same. Write a news report about it.

(c) You are the reporter of The New Age. Two wanted drug dealer were arrested from different parts

of Dhaka. Write a news report about it.

Holiday Homework Class: VIII (Intl), Subject: English Literature

1. Word Meaning:

scullery irrepressible

ensconced viciously

cynical remark skirmishing man oeuvre

hidcony cruelty retreat

confinements vengeance

resolution impromptu celebration

vivacious posthumously

disciples conjured

pasture procured

hurled manger

unanimous resolution expulsion

cryptic answer bleating

indefatigable menacing growls

propulsion persuasively

manipulation

2. Answer the following questions in detail:

a) “I will work harder”- whose motto is this? Why was he admired in the novel ‘Animal Farm’?

Sketch his character.

b) Who is old major? Line a briefing on old major’s speech – Whom does he allegorically represent?

c) Compare and Contract Napoleon a Snowball specially in their leadership qualities.

d) Animal Farm is a children Fable/ Animal Fable – or an Allegorical Satire? Justify your answer.

e) Describe the confession a execution part in chapter VII – What does this incident allegorically

represent.

f) How did the Rebellion take place? What does the rebellion allegorically represent?

g) Which part of the story has a great effect on you- Give reasons for your answer?

h) Who is Snowball? Describe Snowball’s expulsion Part from the Animal Farm. What does this

incident allegorically represent?

3. Answer the following questions in brief:

a) Who is Squealer? How does he advocates for Napoleon- regarding the building of windmill?

b) Who is Squealer? What explanation he gives regarding the milk and the apples?

c) What is Animalism? What are the seven commandments?

d) For what reason did Orwell include the character of Benjamin? What view of life or of society, or

both, does he represent?

e) Contract cloven and Mollie. How do they differ in personality? What does each represent in the

story.

f) Write the summery of the poem ‘Bests of England’.

g) What role do Napoleons- dogs play? How does he use them to control the animals?

h) What is Allegory? What is Satire?

i) What decision Napoleon has taken about the Sunday meetings? What was the reaction of the

animals after this declaration?

j) What is an ode? What picture of abundance do we see in the poem ‘To Autumn’?

k) What is personification? How is Autumn Personified in the poem ‘To Autumn’?

l) According to Keats where can we get the songs of Autumn?

4. Short Notes:

a) Beasts of England

b) Seven Commandments

c) Snowball

d) Napoleon

e) Squealer

f) Benjamin

g) Clover Mollie

h) Mr. Freduich and Mr. Pinkigton

i) Boxer

j) Moses

k) Allegory

l) Sheeps

5. Explanation and ‘Who said to whom’-

a) Remove Man from the scene and the root cause of hunger and overwork is abolished for ever.

b) All men are enemies. All animals are comrades.

c) “Bit and spur shall rust forever, Cruel whips no more shall crack”.

d) “Those ribbons that you are so devoted to are the badge of Slavery. Can you not understand that

liberty is worth more than ribbons?”

e) “Windmill or no windmill, he said, life would go on as it had always gone on-that is badly.”

f) “Do not imagine, comrades that leadership is a pleasure! on the contrary it is a deep and heavy

responsibility.”

g) ‘Never mind the milk, comrades!’ That will be attended to the harvest is more important.

h) `Donkeys live a long time. None of you has ever seen a dead donkey.’

i) `Milk and apples (this has been proved by science, comrades) contain substances absolutely

necessary to the well-being of a pig. We pigs are brainworkers.

j) ‘No sentimentality, Comrade? ‘War is war. The only good human being is a deed one.’

k) “Do not imagine, comrades, the leadership is a pleasure! on the contrary it is a deep and heavy

responsibility.

l) One false step and our enemies would be upon us. Surely, comrades, you do not want Jones bade?

m) ‘His two Slogans, “I will work harder’ and ‘Napoleon is always right, seemed to him a sufficient

answer to all problems.

n) ‘I do not believe that, he said,” Snowball fought bravely at the Baltlc of cowshed. I saw him

myself.”

o) `I warn every animal on this farm to keep his eyes wide open- for we have reason to think that some

of Snowball’s secret agents are lurking among us at this moment.

f) ‘Fools! Fools! Do you not see what is written on the side of that van?

Holiday Homework Class: VIII (Intl), Subject: ICT

CH#16

SYSTEM SECURITY

1. What are the consequences of data loss?

2. Steps for preventing computer theft.

3. What is virus? How to avoid viruses? The role of antivirus.

4. What is called backing up data? Write the rules of backing up.

5. Define: encryption , firewalls , data integrity, data security

6. Fill in the blanks.

CH#20

Controlling things

1. How are robots able to navigate themselves?

2. How do robots avoid colliding with each other and with other objects?

3. How is the power provided?

4. What is sensor? Write the name of the sensors and their uses.

5. Define: buffers, actuators, pseudo code, ABS, data logging

6. What is process control? Write the advantages and disadvantages.

7. What is Navigation systems? Write the benefits and drawbacks of it.

Holyday Homework Subject: Math-I, Class: Std. VIII (Int’l)

1(D)- 1(a,c,m,n,o),2(a,c,k,l),3(b,d,f,k,l),4,5,6,7,8(a,d,f,h,k),9,10

1(E)- 2,3,8,12,16,20,26,27

1(F) - 2,3,4

9(D) – 3(a,b,d,i),7(a,c),8(b,d)

9(E) - 2,4,6,7,10

10(B) - 1 to 4

12(B) – 1 to 12

13(D) – 1(all),2(All),5,7

13(E) – 1(all),2(all),3,4,5(all),6(all),7(all),14,18,19

14(B) – 1(all),2,8

15(D) –1(A to D), 2(B to D)

15(E) – 1(a,b,d,f,k,l)2(a,b,c,e,f)

15(F) – 1 to 12

33.1(A) – 2(I,III,V,VII,IX)

Holyday Homework Subject: Math-II, Class: Std. VIII (Int’l)

3(B) – 1 to 7

4(C) – 2(a,c,e,f),3(all)

4(D) – 3(all)

5(C) – 30 to 44

5(D) – 1 to 46

6(C) – 1 to 12 (except 7)

7(F) – 1(a),2(a,k,l,m,n)

7(G) – 1 to 11

8(B) – 1(D,G),2(D to J)

8(C) – 1 to 10

20.5 -

1 (a) Fig. 8.1 shows a bar magnet suspended by a spring over a coil. The coil is connected to a sensitive centre-zero millivoltmeter.

spring

magnet

coilsensitive

centre-zeromillivoltmeter

Fig. 8.1

(i) The lower end of the magnet is pushed down into the upper end of the coil andheld at rest.

During the movement, an e.m.f. is induced in the coil. The meter shows a deflection tothe right and then returns to zero.

Explain why this e.m.f. is induced.

...........................................................................................................................................

...................................................................................................................................... [1]

(ii) State what happens to the needle of the meter when

1. the magnet is released from rest and is pulled up by the spring,

...................................................................................................................................... [1]

2. the magnet continues to oscillate up and down, moving in and out of the coil witheach oscillation.

...................................................................................................................................... [1]

PhysicsAndMathsTutor.com

Holiday Home WorkSub:PhysicsClass:VIII(Int)

Jahangir

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Jahangir

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Md. Jahangir Alam 01717979515

Jahangir

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(b) Fig. 8.2 shows a transformer.

240 Vmains 8000

turnscoil P coil S

6.0 Vlamp

Fig. 8.2

The primary coil P, connected to the 240 V mains supply, has 8000 turns. The secondary coil S supplies 6.0 V to a lamp.

(i) Calculate the number of turns in the secondary coil.

number of turns = ................................................ [2]

(ii) 1. The current in the primary coil is 0.050 A.

Calculate the power input to the transformer.

power = ................................................ [1]

2. 90% of the power input to the transformer is transferred to the lamp.

Calculate the current in the lamp.

current = ................................................ [2]

[Total: 8]


Jahangir

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2 Fig. 9.1 represents a transformer.

A

coil Scoil P240 Va.c.

8000 turns

B

Fig. 9.1

(a) (i) Name the process by which a changing current in the primary coil P causes a changingcurrent in the secondary coil S.

.......................................................................................................................................[1]

(ii) Suggest a material used for the coils. Explain why this material is used.

...........................................................................................................................................

...........................................................................................................................................

.......................................................................................................................................[2]

(b) The input to the primary coil P is 240 V. This coil has 8000 turns of wire. The voltage obtainedbetween terminals A and B is 12 V.

(i) Calculate the number of turns of wire in the secondary coil S.

number of turns = .........................................................[2]

(ii) The resistor connected between the terminals A and B is replaced by four 12 V lampsconnected in parallel. The current in each lamp is 1.5 A.

Calculate the current in coil P. Assume the transformer is 100% efficient.

current = .........................................................[3]

[Total: 8]


Jahangir

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3 A solenoid is held in a vertical position. The solenoid is connected to a sensitive, centre-zero ammeter.

A vertical bar magnet is held stationary at position X just above the upper end of the solenoid as shown in Fig. 10.1.

magnet

solenoid

S

N

magnet

position X

position Y

A

Fig. 10.1

The magnet is released and it falls through the solenoid. During the initial stage of the fall, the sensitive ammeter shows a small deflection to the left.

(a) Explain why the ammeter shows a deflection.

...................................................................................................................................................

...............................................................................................................................................[1]

(b) The magnet passes the middle point of the solenoid and continues to fall. It reachesposition Y.

Describe and explain what is observed on the ammeter as the magnet falls from the middlepoint of the solenoid to position Y.

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

...............................................................................................................................................[4]


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(c) Suggest two changes to the apparatus that would increase the initial deflection of theammeter.

1. ...............................................................................................................................................

...................................................................................................................................................

2. ...............................................................................................................................................

...................................................................................................................................................[2]

[Total: 7]


Jahangir

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4 Fig. 9.1 shows two separate coils of wire wound around an iron core.

iron core

primarycoil

secondarycoil

Fig. 9.1

An a.c. supply is connected across the primary coil and a 12 V lamp is connected across the secondary coil. The lamp glows with normal brightness.

(a) State the name of the device shown in Fig. 9.1.

...............................................................................................................................................[1]

(b) Explain why there is a current in the lamp.

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

...............................................................................................................................................[4]

(c) (i) The coil connected to the lamp has 450 turns. The e.m.f. of the a.c. supply is 240 V.

Calculate the number of turns on the coil connected to the a.c. supply.

number of turns = ...........................................................[2]

(ii) A 240 V d.c. supply is used instead of the 240 V a.c. supply. Tick one box to indicate whathappens to the lamp.

glows more brightly

glows with the same brightness

glows less brightly

does not glow

[1]

[Total: 8]


Jahangir

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5 (a) Fig. 10.1 shows the gap between the N-pole and the S-pole of a magnet.

N S

Fig. 10.1

The magnetic field in the gap is uniform.

On Fig. 10.1, draw four field lines to show the pattern and direction of the magnetic field in the gap. [2]

(b) Fig. 10.2 shows a horizontal copper wire PQ between two opposite magnetic poles.

Q

P

copperwire

A

N S

Fig. 10.2

A circuit is made by connecting a sensitive digital ammeter between P and Q. The wire PQ

is then moved vertically downwards.


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(i) State and explain what is observed on the ammeter.

...........................................................................................................................................

...........................................................................................................................................

...........................................................................................................................................

.......................................................................................................................................[3]

(ii) State what is observed on the ammeter when PQ is moved

1. vertically downwards at a greater speed,

.......................................................................................................................................[1]

2. vertically upwards at the same speed as in 1.

.......................................................................................................................................[1]

[Total: 7]


Jahangir

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6 The output of an a.c. generator in a power station is 5000 V.

A transformer increases the voltage to 115 000 V before the electrical power is transmitted to a distant town.

(a) State and explain, using a relevant equation, one advantage of transmitting electrical powerat a high voltage.

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

...................................................................................................................................................

...............................................................................................................................................[3]

(b) The transformer contains two coils, the primary coil and the secondary coil.

(i) State the other main component of a transformer and the material from which it is made.

...........................................................................................................................................

.......................................................................................................................................[1]

(ii) State the component in the transformer to which the a.c. generator is connected.

...........................................................................................................................................

.......................................................................................................................................[1]

(iii) There are 400 turns on the primary coil of the transformer.

Calculate the number of turns on the secondary coil.

number of turns = ...........................................................[2]


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(c) Transformers within the town reduce the voltage to 230 V.

Suggest one reason for this.

...................................................................................................................................................

...............................................................................................................................................[1]

[Total: 8]


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1 A strong electromagnet is used to attract pins.

core

pinscoil

current

What happens when the current in the coil is halved?

A No pins are attracted.

B Some pins are attracted, but not as many.

C The same number of pins is attracted.

D More pins are attracted.

2 The diagram shows a transformer.

primary coil800 turns

secondary coil40 turns

inputvoltage

output voltage

The input voltage is 240 V.

What is the output voltage?

A 6.0 V B 12 V C 20 V D 40 V


Holiday Home WorkSub:PhysicsClass:VIII(Int)

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3 A coil carries a current in a magnetic field. The coil experiences a turning effect.

Which device uses this effect?

A

B

C

D

a d.c. motor

an electromagnet

a relay

a transformer

4 A magnet is suspended from a spring so that it can move freely inside a stationary coil. The coil is

connected to a sensitive centre-zero galvanometer.

N

S

spring

moving magnet

stationary coil

centre-zerogalvanometer

The magnet repeatedly moves slowly up and down.

What does the galvanometer show?

A

B

C

D

a constantly changing reading

a steady reading to the left

a steady reading to the right

a steady reading of zero

5 A transformer has 50 turns on its primary coil and 100 turns on its secondary coil. An alternatingvoltage of 25.0 V is connected across the primary coil.

25.0 V



What is the voltage across the secondary coil?

A 12.5 V B 50.0 V C 100 V D 200 V


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6 A wire is placed between the poles of a horseshoe magnet. There is a current in the wire in thedirection shown, and this causes a force to act on the wire.

NSwire

current

magnet

force

Three other arrangements, P, Q and R, of the wire and magnet are set up as shown.

SN

NS

SN

P Q R

magnet turned around current direction reversed current direction reversedand magnet turned around

Which arrangement or arrangements will cause a force in the same direction as the original arrangement?

A P, Q and R B P and Q only C P only D R only


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7 In the circuit shown, only one of the fuses has blown, but none of the lamps is lit.

Which fuse has blown?

A

CBD

powersupply

9 An e.m.f. is induced across a wire when it moves through the magnetic field between the poles ofa magnet.

Which electrical device operates because of this effect?

A a battery

B a cathode-ray tube

C a generator

D a motor

8 What is an advantage of transmitting electricity at a high voltage?

A It is faster.

B It is safer.

C Less energy is wasted.

D Less equipment is needed.


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10 The diagram shows a flat, rectangular coil placed between the poles of a magnet.

There is a current in the coil that makes it turn in the direction shown in the diagram.

N S

coildirectionof turning

current

Which change would make the coil turn in the opposite direction?

A decreasing the current in the coil

B increasing the number of turns on the coil

C reversing both the direction of the current in the coil and the poles of the magnet

D reversing only the direction of the current in the coil

11 A transformer has 1000 turns on its primary coil. An input voltage of 12 V is applied to the primarycoil, and an output voltage of 120 V is induced across the secondary coil.

primary coil1000 turns secondary coil

input voltage12 V

output voltage120 V

How many turns are on the secondary coil of the transformer?

A 100 B 120 C 1000 D 10 000


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12 Which diagram represents the voltage output of a simple a.c. generator?

0

voltage

time

A

0

voltage

time

B

0

voltage

time

C

0

voltage

time

D

13 A step-up transformer is used before electricity is transmitted by overhead cables.

Which statement explains why the step-up transformer is used?

A It increases the current to increase the speed at which the electricity travels.

B It increases the current to reduce energy loss in the cables.

C It increases the voltage to increase the speed at which the electricity travels.

D It increases the voltage to reduce energy loss in the cables.


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14 A current-carrying wire XY lies in the magnetic field between the two poles of a U-shaped

electromagnet. A force acts on the wire XY because of the magnetic field.

current-carrying wire

electromagnet

X

Each of the following actions is carried out separately.

The current in the wire XY is reversed.

The magnetic field is reversed.

Both the current in the wire XY and the magnetic field are reversed at the sametime.

How many of these actions cause the direction of the force on the wire XY to be reversed?

A 0 B 1 C 2 D 3

15 A current-carrying coil in a magnetic field experiences a turning effect.

N S

power supply+ –

coil

How can the turning effect be increased?

A Increase the number of turns on the coil.

B Reduce the size of the current.

C Reverse the direction of the magnetic field.

D Use thinner wire for the coil.


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16 A transformer has 2400 turns on its primary coil and 200 turns on its secondary coil.



output voltage 240 V

What input voltage is needed to give an output voltage of 240 V?

A 12 V B 20 V C 240 V D 2880 V

17 A student investigates electromagnetic induction. She has a bar magnet and a coil of wire that isconnected to a sensitive ammeter.

N S

sensitive ammeter

coil of wire

A

magnet

Which movement does not cause a reading on the ammeter?

A moving the coil to the right

B moving both the magnet and the coil to the left at the same speed

C moving both the magnet and the coil towards each other at the same speed

D moving the magnet to the left


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18 Which device uses slip rings?

A a d.c. electric motor

B a relay

C a transformer

D an a.c. generator

19 The diagram shows a coil of wire connected to a voltmeter.

V

coil of wire

A student has a magnet and an unmagnetised iron rod.

How can an e.m.f. be induced across the coil?

A holding the magnet inside the coil

B holding the iron rod inside the coil

C pushing the magnet into the coil

D pushing the iron rod into the coil

20 A step-down transformer is used to light a 12 V lamp from a 240 V mains supply. The lamp lightsat normal brightness. The primary coil has 600 turns.

240 V 12 V lamp


secondary coil

How many turns are in the secondary coil?

A 12 B 20 C 30 D 50


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21 A steel magnet is placed inside a coil of wire. There is a large alternating current in the coil. Themagnet is slowly moved out of the coil to position P.

steel magnet movedout of coil

12 V a.c.

P

coil of wire

How has the steel changed, if at all, when it reaches position P?

A It has become a stronger magnet.

B It has become demagnetised.

C The poles have changed ends.

D There has been no change.


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22 An electric current is passed through a coil of wire.

coil of wire

Which diagram shows the shape of the magnetic field produced in the middle of the coil?

A B

C D


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23 When a wire is moved upwards between the poles of a magnet, an electromotive force (e.m.f.) isinduced across the ends of the wire.

wire

motionof wire

N

S

Which device uses a moving wire to induce an e.m.f.?

A a cathode-ray tube

B a generator

C a transformer

D an electromagnet

24 An input voltage of 10 V is supplied to the primary coil of a transformer. An output voltage of 40 Vis produced across the secondary coil.

The 10 V supply at the primary coil is now replaced with a 40 V supply.

What is the new output voltage across the secondary coil?

A 10 V B 40 V C 70 V D 160 V


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25 A metal wire is placed between the poles of a magnet.

The wire can be moved in each of three directions OP, QR and ST.

R

T

Q

S

S pole N pole

O

P

metal wire

In which direction or directions must the wire be moved to induce an e.m.f. across the ends of the wire?

A OP only B OP or ST C QR D ST only


Jahangir

Pencil

26 A transformer has 100 turns on its primary coil and 25 turns on its secondary coil. The primarycoil is connected to a 12 V a.c. supply.

100turns

primary coil12 V secondary coil

25turns

What is the voltage induced across the secondary coil?

A 3.0 V B 4.0 V C 48 V D 300 V

27 An input voltage of 10 V is supplied to the primary coil of a transformer. An output voltage of 40 Vis produced across the secondary coil.

The 10 V supply at the primary coil is now replaced with a 40 V supply.

What is the new output voltage across the secondary coil?

A 10 V B 40 V C 70 V D 160 V


Jahangir

Pencil

28 An engineer uses the potential divider shown in the diagram. He needs the output voltage to be1one tenth (10

) of the input voltage.

X

Y outputvoltage

inputvoltage

Which pair of values could he use for the two resistors X and Y?

X / kΩ / kΩY

A 1.0 9.0

B 1.0 10.0

C 9.0 1.0

D 10.0 1.0


Jahangir

Pencil

29 The diagram shows cables used in the transmission of electrical energy. High voltages are usedfor the transmission.

transmission cables

powerstation

Why are high voltages used for the transmission of electrical energy?

A Fear of high voltages stops people from interfering with the cables.

B Heat loss in the cables is smaller than if low voltages are used.

C High voltages increase the current in the cables.

D High voltages produce large magnetic fields, so less insulation is needed.

30 Which diagram shows the magnetic field pattern around a wire that is carrying a currentperpendicular to the page?

A

wire wire

B C D


Jahangir

Pencil

31 The diagram shows a simple transformer with an input of 240 V and an output of 40 V.

There are 600 turns on the primary coil.

output input 600 turns 240 V V40

primary coil secondary coil

How many turns are there on the secondary coil?

A 100 B 320 C 400 D 3600

32 A solenoid is connected to a very sensitive ammeter. A rod is inserted into one end of thesolenoid. The ammeter shows that there is a small electric current in the circuit while the rod is moving.

solenoid rod

A

Which rod is being inserted?

A a heated copper rod

B a magnetised steel rod

C an uncharged nylon rod

D a radioactive uranium rod


Jahangir

Pencil

33 The diagram shows the structure of a transformer.

primary coil

core

Which row shows a suitable material for the primary coil and a suitable material for the core?


Jahangir

Pencil

34 Two soft-iron rods are placed end to end inside a coil which is connected to a battery.

soft-iron rod soft-iron rod

coil

The connections from the battery to the coil are now reversed.

What happens to the soft-iron rods in each case?

battery connections as shown

battery connections reversed

A rods attract rods attract

B rods attract rods repel

C rods repel rods attract

D rods repel rods repel

35 The diagram shows a mains transformer that has an output voltage of 12 V.

240 V a.c.input

12 V a.c.output

coil with1000 turns soft-iron core

How many turns of wire are in the secondary coil?

A 12 B 20 C 50 D 20 000


Jahangir

Pencil

36 The diagram shows an experiment to demonstrate electromagnetic induction.

N S

X

Y

Awire

X and Y are joined, in turn, by four wires, each made of a different material.

Each wire is then moved quickly downwards between the magnets.

Which material will not give rise to an induced current in the wire?

A aluminium

B copper

C iron

D nylon

37 A toy railway engine is driven around a track by a d.c. electric motor.

How can the speed of the motor be increased?

A Use a motor made with fewer turns of wire.

B Use a smaller d.c. voltage.

C Use a stronger magnet in the motor.

D Use the supply with its connections reversed.


Jahangir

Pencil

38 Which diagram shows a movement that will not produce the changing magnetic field needed toinduce an e.m.f. in the coil?

SN

SN

N S

SN

A

B

C

D

moving a magnet and a coil towards each otherat the same speed

moving a magnet and a coil in the same directionat the same speed

moving a magnet away from a fixed coil

moving a coil away from a fixed magnet


Jahangir

Pencil

39 The diagram shows a simple d.c. electric motor which is rotating.

magnetS Nmagnet

coil

Which change will make the motor rotate more quickly?

A increasing the number of turns on the coil

B removing the magnets

C reversing the battery

D reversing the polarity of the magnets

40 A transformer is needed to convert a supply of 240 V a.c. into 4800 V a.c.

NP NS

240 V a.c. 4800 V a.c.

Which pair of coils would be suitable for this transformer?

number of turns on primary coil NP

number of turns on secondary coil NS

A 50 1000

B 240 48 000

C 480 24

D 2000 100


Jahangir

Pencil


core

wire coil

Which materials are suitable to use in its construction?

42 The direction of the current flowing in a straight wire X is into the paper.

Which diagram shows the shape of the magnetic field pattern around the wire?

A BB C

X X X X


Jahangir

Pencil

43 A metal rod PQ rests on two horizontal metal wires that are attached to a battery. The rod liesbetween the poles of a magnet.

P

Q

N

S

metal rod

magnet

magnet

When the switch is closed, the rod moves to the right.

What could be changed so that the rod moves to the left?

A Open the switch.

B Reverse the battery terminals and exchange the poles of the magnet.

C Reverse the battery terminals but without exchanging the poles of the magnet.

D Turn the metal rod around (P and Q exchanged).


Jahangir

Pencil

44 The diagram shows a coil connected to a battery and a switch. Two unmagnetised iron bars hangfreely near opposite ends of the coil.

YX

coil

iron bar iron bar

What happens to the iron bars when the switch is closed?

A Both X and Y move away from the coil.

B Both X and Y move towards the coil.

C X moves towards the coil, Y moves away from the coil.

D Y moves towards the coil, X moves away from the coil.


Jahangir

Pencil

45 A wire passes between the poles of a horseshoe magnet. There is a current in the wire in thedirection shown, and this causes a force to act on the wire.

NSwire

current

magnet

force

Three other arrangements, P, Q and R, of the wire and magnet are set up as shown.

SN

NS

SN

P Q R

magnet turned around current direction reversed current direction reversedand magnet turned around

Which arrangement or arrangements will cause a force in the same direction as the original arrangement?

A P, Q and R B P and Q only C P only D R only

46 The diagram shows a transformer. The input voltage and the number of turns on each coil areshown.

400 turns onprimary coil

800 turns onsecondary coil

200 Va.c.


A 100 V B 200 V C 400 V D 800 V


Jahangir

Pencil

47 Which device uses slip rings?

A a cathode-ray tube

B a d.c. motor

C an a.c. generator

D a solenoid

48 Which graph shows how the output voltage varies with time for a simple a.c. generator?

0

voltage

A

0

voltage

B

0

voltage

C

0

voltage

D

time

time

time

time


Jahangir

Pencil

49 A magnet is suspended from a spring so that it can move freely inside a coil. The coil isconnected to a sensitive centre-zero ammeter.

N

S

spring

centre-zero ammeter

moving magnet

stationary coil

What does the ammeter show when the magnet repeatedly moves slowly up and down?

A a reading constantly changing from left to right and right to left

B a steady reading to the left

C a steady reading to the right

50 The diagram shows a simple step-down transformer used to decrease a voltage.

Which part is the primary coil?

A

BB C D


Jahangir

Pencil

51 Which diagram represents the direction of the magnetic field around a straight wire carrying acurrent out of the page?

A B

current outof page

C D

current outof page


Jahangir

Pencil

52 The diagram shows an a.c. generator.

N S

coil

output voltage

rotationof coil

With the coil in the position shown, the output voltage is +10 V.

When does the output voltage become –10 V?

A when the coil has turned 90°

B when the coil has turned 180°

C when the coil has turned 270°

D when the coil has turned 360°

53 The diagram shows a simple transformer.

core

outputinput

From which material should the core be made?

A aluminium

B copper

C iron

D steel


Jahangir

Pencil

54 What is an electric field?

A a region around a wire carrying an electric current in which a compass needle experiences a force

B a region in which an electric charge experiences a force

C a region in which an electric charge is attracted by the Earth’s gravity

D a region through which electromagnetic radiation is passing

55 A strong electromagnet is used to attract pins.

core

pinscoil

current

What happens when the current in the coil is halved?

A No pins are attracted.

B Some pins are attracted, but not as many.

C The same number of pins is attracted.

D More pins are attracted.


Jahangir

Pencil




inputvoltage

output voltage

The input voltage is 240 V.


A 6.0 V B 12 V C 20 V D 40 V

57 The diagram shows a shaded area where the direction of a magnetic field is into the page.

A beam of β-particles enters the field as shown.

magnetic fieldinto the page

beam ofβ-particles

In which direction is the beam of β-particles deflected as they enter the magnetic field?

A

B

C

D

into the page

out of the page

down the page

up the page


Jahangir

Pencil

58 An electron moves into a uniform magnetic field.

The arrow shows the initial direction of motion of the electron.

The direction of the magnetic field is into the plane of the page (away from you).

uniformmagnetic field

electron

In which direction does a force act on the electron when it enters the magnetic field?

A into the page

B out of the page

C towards the bottom of the page

D towards the top of the page


Jahangir

Pencil

59 The diagram shows an a.c. generator.

N S

coil

output voltage

rotationof coil

As the coil passes through the position shown, the output voltage is +10 V.

When does the output voltage become –10 V?

A when the coil has turned through 90°

B when the coil has turned through 180°

C when the coil has turned through 270°

D when the coil has turned through 360°


Jahangir

Pencil

60 A solenoid is connected in series with a sensitive ammeter. The N pole of a magnet is placednext to one end of the solenoid, marked X.

magnet

solenoid

A

XN

First, the N pole of the magnet is pushed towards X, then the magnet is pulled away from X. During both stages the ammeter deflects.

Which type of magnetic pole is induced at X during these two stages?

as N pole moves towards X

as N pole moves away from X

A

B

C

D

N pole

N pole

S pole

S pole

N pole

S pole

N pole

S pole


Jahangir

Pencil


soft-iron core

primarycoil

secondarycoil

Which row describes the magnetic field in the soft-iron core and the magnetic field in the secondary coil when the transformer is operating?

magnetic field

in soft-iron core in secondary coil

A

B

C

D

changing

changing

constant

constant

changing

constant

changing

constant


Jahangir

Pencil

62 The diagram shows a wire placed between two magnetic poles of equal strength.

A current passes through the wire in the direction shown. The current causes a downward force on the wire.

wire

directionof current

directionof force

What is the arrangement of the magnetic poles?

S NA

N SB

N NC

S SD


Jahangir

Pencil

GCSE Physics for You, 5th edition© Keith Johnson & Sue Holt Jahangir Alam-01717979515

Use these questions to help you revise (cover the right-hand side with a sheet of paper).

1 What is an electric current? (pages 255, 258) ... a flow of electrons (–), moving from the negative terminal to the positive terminal.

2 Where in a circuit should you put an ammeter?

(p. 256) ... in series with the component whose current

you want to measure. 3 Where in a circuit should you put a voltmeter?

(p. 258) ... in parallel, across the component whose p.d.

you want to measure.

4 Draw a circuit diagram of a cell, switch, lamp, ammeter and variable resistor in series. (p. 254, 256, 261)

...

5 When a p.d. of 10 V is applied across a resistor, 2 A flows. What is the resistance? (p. 259)

... resistance, R I

V

current,

p.d.,=

) 5( ohms 5A 2

V 10==

6 A resistance of 4 is carrying a current of 2 A,

and is in series with a resistor of 6 . What is the total resistance and what is the current through the 6 resistor? (p. 262)

... total resistance = 4 + 6 = 10 current through each resistor (in series) = 2 A

7 A resistor of 2 is in parallel with a resistor ... the smaller resistor (2 ) has the bigger

of 4 . Which resistor has the bigger current? (p. 263)

current. (It will be twice as big.)

8 In the diagram,

each cell has a p.d. of 1.5 V. What is the total p.d.?

... 6 V

9 What does the gradient of a current–voltage

tell you? (p. 265) ... the steeper the graph, the less the

resistance. 10 Why is the current–voltage graph for a

filament lamp a curved line? (p. 265) ... as more current flows, the metal filament

gets hotter, so its resistance increases, so the graph gets flatter.

11 A current of 2 A flows for 1 minute.

How much charge flows? (p. 266) ... charge, Q = current, I time, t = 2 A 120 s = 240 C

12 100 coulombs flow from a 2 V cell. ... energy transferred, E = p.d., V charge, Q

= 2 V 100 C = 200 joules

How much energy is transferred? (p. 267)

Revision QUIZ 31 Circuits

Oxford University Press, ISBN 978-0-19-837571-5 GCSE Physics for You, 5th edition © Keith Johnson & Sue Holt

36 Electromagnetic induction

Use these questions to help you revise (cover the right-hand side with a sheet of paper).

1 What happens if a magnet is pushed into a coil? (page 303)

... a voltage is induced in the coil (and a current flows if there is a complete circuit).

2 What happens if this magnet is pulled out of

the coil? (p. 303) ... the current flows the opposite way.

3 How could the current be increased? (p. 303) ... by using:

• a stronger magnet • a quicker movement • more turns on the coil.

4 What is the difference between a.c. and d.c.?

(p. 305) ... d.c. = direct current, like the current from

a battery. It flows one way. a.c. = alternating current, as in the mains. It is constantly changing direction.

5 What can you say about the electricity in the

mains? (p. 305) ... it is a.c., at a frequency of 50Hz.

Its effective voltage is 230V (and its peak voltage is 320V).

6 How could the voltage (and the current) from

an a.c. generator be increased? (p. 306) ... by using:

• a coil with more turns • a stronger magnetic field • a coil turning faster • a coil with a bigger area.

7 Why is a high voltage used for the power lines

in the National Grid network? (p. 309) ... the higher the voltage, the smaller the

current needed to transfer energy at the same rate. A smaller current means less energy is wasted (in heating up the power lines).

8 Why is a.c. used in the mains and the National

Grid? (p. 309) ... so that transformers can be used (they do

not work with d.c.). 9 A transformer has a primary coil with 20 turns

and a secondary coil with 100 turns. If the primary voltage is 3V, what is the secondary voltage? (p. 308)

... It is a step-up transformer (ratio 1:5)

10

If this transformer is 100% efficient, and 1A is flowing in the primary, what current can flow in the secondary? (p. 308)

... if the voltage is stepped-up by 1:5, then the current is stepped-down by the same ratio, to amp (0.2A).

Revision

QUIZ

secondary voltage

primary voltage

number of turns on secondary

number of turns on primary =

secondary voltage

3 V =

100

20

secondary voltage = 15 V

51

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