Edexcel Science 2011 P1 Topic 5 Exercise

7/28/2019 Edexcel Science 2011 P1 Topic 5 Exercise

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Surname Name

QUESTIONS & EXERCISES

Topic 5 Generation and Transmission of Electricity_______________________________________________________________________________________

1. (a) Join each term on the left to one correct description on the right.

[2 marks]

The energy carried by 1 Coulomb of charge

Current The force pushing charge in a circuit

Voltage The rate of flow of charge

The speed of electrons in a circuit

(b) Below we see a graph of the amount of charge flowing in a circuit with time.

(i) We define current in Amps as the charge that flows in 1 second.Use the graph to find the current in the circuit.

[2 marks]

Current = A

(ii) In the sentences below circle the correct part in italic.

[2 marks]

The straight line through the origin shows that charge

{ isproportional to / isdirectly proportional to / increases but not proportionally with } time.

It also shows that current is { constant/ decreasing/ increasing}.

(iii) Draw a second line on the same graph to show how charge would flow with timeif the current becomes larger.

[1 mark]

0

1

2

3

4

5

0 2 4 6 8 10

Charge (C)

Time (sec)


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(c) Such small currents can be produced by solar cells.Explain whether solar cells use a renewable or a non-renewable energy sourceand discuss their advantages and disadvantages.

[4 marks (EW)]

(d) Put a cross ( ) in the box next to the correct answer.

[1 mark]

Look at the two statements below.

Statement 1: Nuclear power uses renewable sources

Statement 2: Geothermal uses renewable sources

Which statement(s) is (are) correct?

A Statement 1 only

B Statement 2 only

C Both statements

D Neither


[1 mark]

Look at the two statements below.

Statement 1: Solar cells produce DC

Statement 2: Wind turbines produce DC

Which statement(s) is (are) correct?

A Statement 1 only

B Statement 2 only

C Both statements

D Neither

[Total for Q1 = 13 marks]

_______________________________________________________________________________________


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2. The graphs below show the amount of transferred energy with chargeand flow of charge with time.

(a) (i) Describe the relationship between energy and charge in terms of proportionality

and explain why you think it is so.[3 marks]

(ii) The voltage can be calculated by

Charge

EnergyVoltage

Use the appropriate graph to calculate Voltage.

Write the unit.[2 marks]

Voltage =

(ii) The Current in Amps can be calculated by

(sec)Time

(C)Charge(A)Current

Use the appropriate graph to calculate Current.

Be careful with units.[3 marks]

Current = A

0

200

400

600

800

1000

0 40 80 120 160 200

Energy(J)

Charge (Q)

0

40

80

120

160

200

240

0 0.5 1 1.5 2

Charge(C)

Time (min)


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(b) (i) Put a cross ( ) in the box next to the correct answer.

[1 mark]

Which is equivalent to the unit of power?

A J

B kWh

C J/s

D W/s

(ii) Use your answers in (a) to calculate the power in the electrical circuit.Write the unit.

[2 marks]

Power =

(iii) Find how much energy would be produced if the circuit kept working for an hour.Be careful with units.

[2 marks]

Energy =

(c) It takes a 1.5 kW water kettle 5 min to boil water.A 50 W fun will use the same amount of energy in 2.5 hours.

(i) Calculate the energy each of the device uses.

[2 marks]

Energy =

(ii) Put a cross ( ) in the box next to the correct answer.

[1 mark]Which statement correctly explains the observation in (i)?

A The kettle uses more energy per second

B The fun uses more energy per second

C The kettle uses less power

D The fun uses more current


_______________________________________________________________________________________


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3. (a) A 60 W fun is connected to 240 V mains.Air conditioning systems are also connected to the mains.

(i) Calculate the current that the fun uses.Write the unit.

[2 marks]

Current =

(ii) An air conditioning unit uses 9 A.Calculate the input power of the air conditioning unit.Explain why the Electricity Authority urged people to use funs instead of air conditioners.

[3 marks]

Power =

(b) (i) Put a cross ( ) in the box next to the correct answer.

[1 mark]

A generator changes

A kinetic energy to sound energy

B chemical energy to electrical energy

C electrical energy to thermal energy

D kinetic energy to electrical energy

Below you on the left you can see a generator.

(i) Mark on the picture where the magnets are.

[1 mark]

(ii) The induced voltage is directly proportional to the number of coils.

Sketch on the axes on the right the graph of induced voltage against number of coils.[2 marks]

induced

voltage

number of coils


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(iii) Explain how the strength of the magnet affects the induced voltage.

[1 mark]

(c) Below you can see how the current produced by the generator changes with time.

(i) Explain whether this type of current is AC or DC.

[2 marks]

(ii) On the same graph Draw how the current would change with time if the coilrotated faster.

[2 marks]

(iii) Below you see the original current in dotted line.

Describe one change that will cause the generator to produce the current

shown by the thick line?[2 marks]


_______________________________________________________________________________________

time

current

time

current


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4. (a) Below you see two different types of currents.

(i) State whether Current A is AC or DC.

[1 mark]

(ii) Explain whether Current B is AC or DC.

[2 marks]

(ii) Name a source that produces

[2 marks]

Current A:

Current B:

(b) Below we see how voltage can be induced by moving a magnet backwards.

For each of the cases below draw the new reading of the voltmeter.

[3 marks]

time

currentcurrent

time

A B

The magnet movesback at the same speed

with poles reversed

The magnet movesforward at higher speed

with poles reversed

The magnet movesforward at the same

speed with more coils

(i) (ii) (iii)


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(b) Below we see a schematic picture of how electricity is produced in a conventional power station.

(i) Describe what the generator is made of that makes it produce electricity.

[3 marks]

(ii) Explain what a conventional power station is.Discus the advantages and disadvantages of such power stations.

[6 marks (EW)]


_______________________________________________________________________________________

BoilerBurns fuelto turnwater to steam

Turbine

Rotates by the steam

GeneratorProduces

electricity


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5. (a) The picture below shows another energy source used today.

(i) How do we call these devices?What energy source do they use and where does it originate from?State whether it is renewable or non-renewable.Suggest why the devices are shown to be in the countryside.

[4 marks (EW)]

(ii) Describe one disadvantage of the system shown above.[1 mark]

(b) Put a cross ( ) in the box next to the correct answer.

[1 mark]

Below you can see a schematic picture of a geothermal power station.

The geothermal power station

A is used primarily to produce heat

B uses a renewable sources

C uses a non-renewable source

D gets its original energy from the Sun

Water sent below

ground through pipes Water heated by underground heat and turned

to steam, gathered by pipes and sent up

Steam rotates turbine and generator


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(c) Below you see a schematic picture of a hydroelectric power station.

(i) Name the primary energy source for this station and therefore state whetherit is renewable or non-renewable.

[2 marks]

(ii) Hydroelectric power stations have great impact on the environment.Explain why.

[2 marks]

(iii) Discuss one further disadvantage of the hydroelectric power station.[2 marks]


[1 mark]

The energy used up from the electricity mains is measured in

A J/s

B kW

C W/s

D kWh


_______________________________________________________________________________________

Water

Clouds

Rain

Mountain

River

Dam

Generator


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6. Below you can see the basic structure of a transformer.

(a) (i) Explain the difference in construction between a step up and a step down transformer.

[2 marks]

(ii) The current in the primary coil is AC.Is the current in the secondary coil AC or DC?

[1 mark]

(iii) ForI1 = 15 A and V1 = 200 V calculate the input power,P1.

[2 marks]

Input Power,P1=

(iv) If there are no energy losses in the transformer state the output powerP2in the secondary coil

[1 mark]

Output Power,P2=

(v) The number of turns in the primary coil isN1 = 300.The number of turns in the secondary coil isN2 = 6000.

Calculate the voltage V2 and the currentI2 in the secondary coil.Assume there are no energy losses in the transformer.

[4 marks]

Output Voltage, V2=

Output Current,I2=

Primary coil Secondary coil

iron core

Number of primary turnsN1 Number of secondary turnsN2

Primary Current =I1

Primary Voltage = V1

Secondary Current =I2

Secondary Voltage = V2


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(b) The more the current the greater the energy lost in the wires as heatduring transmission of electricity.Based on your results in (a) explain why there is a step up transformerbefore electricity is transmitted over long distances.

[4 marks (EW)]

(c) (i) Electricity going to homes has an original voltage of 33 000 V.The voltage at the output that reaches the mains at home is 230 V .To drop the voltage they use a transformer with a primary number of coilsN1 = 20 000.

Find the number of secondary coilsN2.[2 marks]

Number of secondary coils,N2=

(ii) Explain why it is necessary to use a step down transformer before it isdistributed to our homes.

[2 marks]

(iii) Explain why it is important to save fossil fuel.[2 marks]


_______________________________________________________________________________________


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7. (a) Put a cross ( ) in the box next to the correct answer.

[1 mark]

The picture shows a power station and the step up transformers used before electricitygets distributed over large distances in the National Grid.

The transformers are used because they increase

A current

B efficiency

C energy

D heat losses

(b) Before electricity reaches our homes it has a voltage of 33 000 V.Explain why such a voltage is dangerous and how it is lowered.

[3 marks]

(c) Mary uses a 750 W hair drier every day for 5 min.She wants to find out how much its use costs per month.

(i) Find the number of hours the hair drier is used in 1 month (30 days).

[1 mark]

Number ofhours =

(ii) Find the total cost of using the hair drier for a month.

Electricity cost = 8 p per kWh.[3 marks]

Cost =

(iii) Find the equivalent of 1 kWh in Joules.[2 marks]

1 kWh = J

Step up transformers


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(iv) Find how much time the hair drier should work to use up 1 kWh of energy.

[2 marks]

Time =

(b) The elevator in an apartment building uses 12 A current at a voltage of 230 V.Electricity comes at a cost of 8 p per kWh.The management does not want to pay more than 600 per year for using the elevator.

(i) Find the maximum time that the elevator must be in use per year so that the amount paiddoes not exceed 600 per year.

Be careful with units and conversions.[5 marks]

Time =

(ii) The management wants to install a new elevator.It costs 23 000 but its use will only cost 450 per year.Calculate the pay-back time for the new elevator.

[2 marks]

Pay-back time =

(iii) Describe two advantages of the new elevator compared to the old one.

[2 marks]

1.

2.


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8. (a) Below you see photographs of two different types of lamps.

filament lamp energy-saving lamp

They both produce the same amount of light energy in the same time.The surface temperature of the lamps changes after they have been switched on.The graph shows this information for both lamps.

(i) At maximum brightness the filament lamp has a surface temperature equal to 125 C.

What is the surface temperature of the energy-saving lamp at maximum brightness?[1 mark]

Temperature = C

(ii) Use the graph to describe one advantage of the energy-saving lamp.[2 marks]

(iii) Use the graph to describe one disadvantage of the energy-saving lamp.

[2 marks]

0

25

50

75

100

125

150

0 0.5 1 1.5 2 2.5

Surfacetemperature

(deg Celsius)

Time after switching on (sec)

filament lamp

energy-saving lamp


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(b) Below you see a table of costs and savings for various energy reducing measuresthat Peter can introduce in his home.

Energy saving measure Cost () Saving per year () Pay-back time (years)

Double glazing windows 4000 400

Loft insulation 120 2

Draught proofing 40 1.5

(i) Complete the table above calculating the missing values.

[3 marks]

(ii) Name the most cost-effective measure.

[1 mark]

(iii) Besides cost-effectiveness, give one reason why Peter would choose to installdouble-glazing first before other measures.

[1 mark]

(iv) Besides cost-effectiveness, give one reason why one would choose to buy

draught-proofing first before other measures.[1 mark]

(v) Peter pays 2650 per year for electricity.Find how much Peter would pay for electricity annually if he makes all the changesin the above table.

[2 marks]

New cost =


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Edexcel Science 2011 P1 Topic 5 Exercise

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