Test sheet :Physics -current and electrostat 26 june 13 @Viresh

7/28/2019 Test sheet :Physics -current and electrostat 26 june 13 @Viresh

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Test:12th:26 june-13

Passage for Q No 1 and 2 :In the circuit shown, the cell has no internal resistance and all other resistances

are marked against each resistor.

1- Out of A and B ,which point will be at higher potential?

(a) A (b) B

2-What is the potential difference VA VB ?

(a) 2 volt (b) -2 volt (c) 1 volt (d) -1 volt

Passage for Q No 3 ,4 and 5 :Three identical bulbs A, B and C each of rated power 100 Watt/230 volt , are

connected as shown. The battery shown has no resistance.

3- If the actual power of the bulb A is 100 watt, what is the actual power of the bulb B ?

(a) 100 watt (b) 200 watt (c) 50 watt (d) 25 watt

4-- If the actual power of the bulb A is 100 watt, what is the emf of the battery ?

(a) 460 volt (b) 230 volt (c) 345 volt (d) 690 volt

5-If the bulb C gets fused , the power of the

(a) bulb A increases and that of B decreases (b) bulb A decreases and that of B increases

Passage for Q No 6 and 7 :Three identical cells are placed in series supporting one another. This combination

is used to draw current in a circuit of variable resistance (say R ). The terminal

potential V of the combined cells is plotted (as in the fig shown), with the

current i drawn from the cells combination.

6-What is the internal resistance of any one cell ?

(a) 1 ohm (b) 2 ohm (c) 9 ohm

7-What power is consumed in the circuit when the current drawn is 6 ampere ?

(a) 27 watt (b) 81 watt (c) 54 watt

Passage for Q No 8 and 9 :In the circuit shown, the cels shown are of emfs 6 volts and 4 volts with internal resistance same as

2 ohm . The expression of the current in the resistor R is found as

x / ( y + R ) where x is in volts and y in ohm .

8-The values of x and y are respectively

(a) 5 and 2 respectively (b) 5 and 1 respectively

9- If the resistance R is made as large as infinity, potential difference between the

points a and b will become

(a) x (b) 0 (c) lesser than x but not zero


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In following question from question no 10 to 14 fill in the blanks with the appropriate words or

numbers :

10-If two unequal resistances in series have equivalent resistance 20 ohm , then their parallel

combination will have resistance ( lesser/ greater ) than 5 ohm.

11-A homogenous wire with non uniform cross section is connected to a cell. Out of the quantities

current, current density and the electric field , at each section the quantity .. remains same .

12-If the electric field in a wire is doubled, the drift velocity of its conduction electrons will increase

by ..percent.

13-If the temperature rise reduces the electric permittivity of an insulator, then it is a .( polar/non

polar )

14-In electrostatic condition, the sharper end of a conductor carry .( more / lesser ) charge

density.

In following question from question no 15 to 20 mark true/false

15- Alloys have more temperature coefficient of resistance.

16-In meter bridge, readings will give more correct estimate of unknown resistance if the null point is

close to the middle of the middle of meter bridge wire.

17-When a resistance is connected in parallel with any other resistor, effective resistance decreases.

18-Capacitors connected in series stores energy in ratio directly proportional to their capacitances.

19-The charges of a parallel plate capacitor carrying equal and opposite charges , reside on inner

faces.

20-If two opposite charges move away, electrostatic potential energy due to their electrostatic

interaction increases.

In following question from question no 21 to 30 choose the most correct alternative :

21- A wire whose resistance R can be varied, is connected to a cell of non

internal resistance. If the resistance R is varied, the terminal potential V of the

cell vary with R according to the graph

(a) 1 (b) 2 (c) 3

22- Two capacitors of capacitances C and 3 C are charged up to voltage V and V/2 respectively.

Now their plates of unlike charges are mutually connected and some time their potential become

same and equal to

(a) V/4 (b) V/6 (c) V/8


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23-An electron is released from rest at distance 30 cm from afixed proton. The electron is found

moving with kinetic energy E when it is at distance 20 cm from the proton. When the electron

reaches at distance 10 cm from the proton, kinetic energy will be

(a) 2 E (c) 3 E (c) 4 E

24- Two cells of same emf but of different internal resistances 3 ohm and 7 ohm

are connected as shown. The terminal potential of the second cell becomes zero

when the resistance R becomes

(a) 5 ohm (b) (21)1/2 ohm (c) 4 ohm

25- A parallel plate capacitor with separation d between the plates, is filled with two different

dielectrics of dielectric constants K and 3 K each with thickness d/2 . The equivalent dielectric

constant of the system is

(a) 1.5 K (b) 2K (c) 0.75 K

26- Three identical resistors are connected as in the fig. Any one resistor gets

spoiled if the power in it exceeds 30 watt. What maximum total power

can be obtained from this circuit ?

(a) 90 watt (b) 30 watt (b) 45 watt

27- A long thin cylinder of radius R carry surface charge density . What will be the electric field at

distance 2 R from the axis of the cylinder ?

(a)

/

0 (b) 0.5

/

0 (c) 0.25

/

0

28- The expression - p E cos with symbols having usual meaning, stands for

(a) electrical potential energy of dipole (b) Electric torque on dipole

29- In the circuit shown, the both cells have zero internal resistance. What are

the currents in cells of 8 Volt emf and 2 Volt ?

(a) 2 A and 1.5 A respectively (b) 2 A and 0.5 A respectively

30-A copper wire and zinc wire of same area and different lengths are connected in series to a

cell. The electric conductivity of copper is more than that of the zinc . Electric field in the copper

(a) will be same as in zinc (b) will be lesser than in the zinc (c) will be more than in the zinc


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Following Q31 to Q35 have one or more correct options:

31- In the circuit shown both cells have emf E and no internal resistance .

(a) The current in the 3 R resistor is zero.

(b) Potential at B is higher than at A

(c) Potentials at A and B will be differing by E

32- Refer the circuit which contains resistors of either 5 ohm or 10 ohm only

(a) Current in the vertical resistor of 5 ohm will be zero.

(b) The current I2 = 1.5 I1

(c)If the vertical resistor of 5 ohm is removed, currents I1 and I2 will become same.

33- (a) Alloys of metals usually have lesser resistivity than that of their

constituent metals.

(b) Alloys usually have much lower temperature coefficients of resistance

than pure metals.(c) The resistivity of the alloy manganin is nearly independent of temperature.

34-A potentiometer has driver cell of emf 12 volt and internal resistance 4 ohm. The potentiometer

wire has length 4 m and resistance 16 ohm.

(a) Potential gradient in the potentiometer wire is 48 /25 volt/meter.

(b)half of the potentiometer wire length will balance a cell of emf 4.8 volt

(c)If the potentiometer wire is replaced by a wire of double resistivity and double area but of same

length, potential gradient will not change.

35-There are few identical cells , each of internal resistance 0.5 ohm and emfE. The cells are arrangedin a parallel combination of n rows , each row containing m cells in series . The combination is

connected across a resistor of 3 ohm.

(a) Effective emf of this combination of cells is mE

(b) Effective internal resistance of the cells is mr/n

(c) The current in the resistor of 3 ohm will be given by the expression m E /( 3+0.5 m /n )

END

Test sheet :Physics -current and electrostat 26 june 13 @Viresh

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