EXERCISE - 01 MCQ (SINGLE CHOICE CORRECT)

1. A wire in the form of a tetrahedron. The resistance of each edge is r. The equivalent resistances between corners 1-
2 and 1-3 are respectively.
4
r r
(A) , (B) r, r
2 2
1 3
r r
(C) ,r (D) r ,
2 2 2

2. In the circuit shown in figure, ammeter and voltmeter are ideal. If E = 4V, R = 9 and r = 1, then readings of
ammeter and voltmeter are

V
R R R
E1,r

(A) 1A, 3V (B) 2A, 3V (C) 3A, 4V (D) 4A, 4V

3. Find the potential diffeence across the capacitor in volts.

(A) 7
(B) 8
(C) 9
(D) 10

4. An insulating pipe of cross–section area 'A' contains an electrolyte which has two types of ions : their charges being
–e and +2e. A potential difference applied between the ends of the pipe result in the drifting of the two types of ions,
having drift speed = v (–ve ion) and v/4 (+ve ion). Both ions have the same number per unit volume = n. The current
flowing through the pipe is
(A) nev A/2 (B) nev A/4 (C) 5nev A/2 (D) 3nev A/2

5. All resistances in the diagram below are in ohms. Find the effective resistance between the point A and B (in ).

(A) 1 (B) 0 (C) 3 (D) 2

6. A battery of internal resistance 4 is connected to the network of resistance as shown. In order that the maximum
power can be delivered to the network, the value of R in  should be :–

R R
R 6R R
E
4
R 4R

(A) 2 (B) 3 (C) 4 (D) 1

7. An uncharged capacitor of capacitance 100 µF is connected to a battery of emf 20V at t = 0 through a resistance
10 , then time at which the rate of energy stored in the capacitor is maximum :
(A) (4 in 2) ms (B) (2 in 2) ms (C) (In 2) ms (D) (3 In 2) ms

8. In the above question the maximum rate at which energy is stored in the capacitor is :
(A) 10 J/s (B) 20 J/s (C) 40 J/s (D) 5 J/s

9. In the diagram shown, all the wires have resistance R. The equivalent resistance between the upper and lower
dots shown in the diagram is

1 2
3

(A) R/8 (B) R (C) 2R/5 (D) 3R/8

10. If X, Y and Z in figure are identical lamps, which of the following changes to the brightness of the lamps occur when
switch S is closed?

Z
X S

(A) X stays the same, Y decreases (B) X increases, Y decreases

(C) X increases, Y stays the same (D) X decreases, Y increases

11. A battery of internal resistance 2 is connected to a variable resistor whose value can vary from 4 to 10 .
The resistance is initially set at 4. If the resistance is now increased then–
(A) power consumed by it will decrease
(B) power consumed by it will increase
(C) power consumed by it may increase or may decrease
(D) power consumed will first increase then decrease

12. In the circuit shown in figure reading of voltmeter is V1 when only S1 is closed, reading of voltmeter is V2 when
only S2 is closed and reading of voltmeter is V3 when both S1 and S2 is closed and reading of voltmeter is V3
when both S1 and S2 are closed. Then

(A) V3 > V2 > V1 (B) V2 > V1 > V3 (C) V3 > V1 > V2 (D) V1 > V2 > V3
13. The time constant of the shown circuit for charging is

5 5 7 7
(A) RC (B) RC (C) RC (D) RC
3 2 4 3

14. A storage battery is connected to a charger for charging with a voltage of 12.5 volts. The internal resistance of the
storage battery is 1.When the charging current is 0.5 A, the emf of the storage battery is
(A) 13 volts (B) 12.5 volts (C) 12 volts (D) 11.5 volts

15. In the figure shown the power generated in y is maximum when y=5then R is

10V,
2
R

(A) 2 (B) 6 (C) 5 (D) 3

16. A circuit is comprised of eight identical batteries and a resistor R = 0.8. Each battery has an emf of 1.0 V and
internal resistance of 0.2. The voltage difference across any of the battery is

R=0.8

(A) 0.5 V (B) 1.0V (C) 0V (D) 2V

17. The heat produced in the capacitors on closing the switch S is

(A) 0.0002 J (B) 0.0005 J (C) 0.00075 (D) Zero

18. A galvanometer coil has a resistance 90 and full scale deflection current 10mA. A 910  resistance is connected in
series with the galvanometer to make a voltmeter. If the least count of the voltmeter is 0.1V, the number of divisions
on its scale is
(A) 90 (B) 91 (C) 100 (D) None
19. For the circuit shown here, the potential difference between points A and B is

(A) 2.5 V (B) 7.5 V (C) 10 V (D) Zerp

20. By error, a student places moving–coil voltmeter V (nearly ideal) in series with the resistance in a circuit in order to
read the current, as shown. The voltmeter reading will be

E=12V,r=2

4
v

(A) 0 (B) 4V (C) 6V (D) 12V

21. A Wheatstone's bridge is balanced with a resistance of 625 in the third arm, where P, Q and S are in the 1st, 2nd
and 4th arm respectively. If P and Q are interchanged, the resistance in the third arm has to be increased by 51to
secure balance. The unknown resistance in the fourth arm is

P Q

G
S 625 

(A) 625  (B) 650 (C) 676 (D) 600

22. A charged capacitor is allowed to discharge through a resistor by closing the ey at the instant t = 0. At the instant t
= (  n4)µs, the reading of the ammeter falls half the initial value. The resistance of the ammeter is equal to -

C=0.5µF
+ –

A
2

(A) 1M (B) 1 (C) 2 (D) 2M

23. A 3 mega ohm resistor and an uncharged 1µF capacitor are connected in a single loop circuit with a constant source

of 4 volt. At one second after the connection is made what are the rates at which energy is being delivered by the

source ?

(A) 16(1–e1/3) µ J/s (B) 16µ J/s

(C) 16/3 e1/3 µ J/s (D) 16/3(1–e1/3) µ J/s

24. In the given potentiometer circuit length of the wire AB is 3m and resistance is R=4.5. The length AC for no
deflection in galvanometer is

E=5V r=0.5

R=4.5
A B
C

G
E1=3V r1

(A) 2m (B) 1.8m (C) dependent on r1 (D) None of these

25. In the circuit given, find the potential of the point P so that the current throught battery of 4 V is zero.

(A) 31V (B) 35V (C) 15V (D) 11V

26. A constant voltage is applied between the two ends of a uniform metallic wire. Some heat is developed in it. The heat
developed is doubled if
(A) both the length and the radius of the wire are halved
(B) both the length and the radius of the wire are doubled
(C) the radius of the wire is doubled
(D) the length of the wire is doubled

27. A capacitor C = 100 µF is connected to three resistor each or fesistance 1k and a battery of emf 9V. The switch S
has been closed for long time so as to charge the capacitor. When switch S is opened, the capacitor discharges with
time constant -

(A) 33 ms (B) 5 ms (C) 3.3 ms (D) 50 ms

28. Charge q versus t graph for a capacitor, initially uncharged is charged with a battery of emf 5V as shown in figure. The
resistance R of the circuit is

(A) 2M (B) 6M (C) 3M (D) 1.5M

29. The equivalent resistance of a group of resistances is R. If another resistance is connected in parallel to the group, its
new equivalent becomes R1 and if it is connected in series to the group, it new equivalent becomes R2 we have
(A) R1>R or R2>R (B) R1<R or R2>R (C) R1>R or R2<R (D) R1<R or R2<R

30. The net emf and internal resistance of three batteries as shown in figure is :

2 8V

3V
A B


2 10V

(A) 2V, 1 (B) 2V, 2 (C) 2V, 1.5 (D) 4V, 2

ANSWERS
EXERCISE - 01
1. A 2. A 3. B 4. D 5. D
6. A 7. C 8. A 9. D 10. B
11. A 12. B 13. C 14. C 15. D
16. C 17. D 18. C 19. A 20. D
21. B 22. C 23. C 24. A 25. A
26. B 27. D 28. D 29. B 30. B