Slide 1 / 25

1 The induced emf in a closed coil of wire, according to Faraday’s Law, is proportional to:

A I

B II

C II and II

D III and IV

E IV

I. The magnitude of the magnetic flux

II. The magnetic flux density

III. The number of turns

IV. The rate of change of magnetic flux

Slide 2 / 25

2 A changing magnetic field B induces an emf Ɛ in a coil of radius R. What is the induced emf in the coil of radius 2R?

A ε

B 2ε

C 4ε

D ε /2

E ε /4

Slide 3 / 25

3 A uniform magnetic field is distributed in a space of a circle of radius r. The changing field induces an emf Ɛ in the loop with the radius r. What is the induced emf in the loop with the radius 2r?

A ε

B 2ε

C 4ε

D ε /2

E ε /4

Slide 4 / 25

4 The number of turns in a long solenoid is doubled, how does the inductance of the solenoid change?

A It doesn't change

B It doubles

C It quadruples

D It is cut to a half

E It is cut to a quarter

Slide 5 / 25

5 Which of the following is true about the inductors?

A I

B III

C I and II

D II and III

E All of the above

I. They store energy over a long time

II. They resist the flow of current through it

III. They can produce a magnetic field

Slide 6 / 25

6 Which of the following can act as an inductor?

A I

B III

C I and II

D II and III

E All of the above

I. A long coil

II. A long wire

III. A conducting sphere

Slide 7 / 25

7 At time t =0 the switch is closed. Which of the following graphs best describes the voltage V across the resistance R as a function of time t?

A B

CD

E

Slide 8 / 25

8 If L is inductance measured in H (Henry), what is 1 H is equivalent to?

A 1 Vs/A

B 1 A/Vs

C 1 AV/s

D 1 As/V

E 1 s/AV

Slide 9 / 25

9 If R is 1 Ω and L is 1 H, then L/R is

A 1 V

B 1 F

C 1 A

D 1 C

E 1 s

Slide 10 / 25

10 In the circuit above, what is the instantaneous current at point P after the switch is closed?

A ε/R

B 2ε/R

C ε/2R

D Lε/R

E 0

Slide 11 / 25

11 In the circuit above, what is the current at point P after the switch is closed for a long time?

A ε/R

B 2ε/R

C ε/2R

D Lε/R

E 0

Slide 12 / 25

12 The switch is closed for a long time in the circuit above, what is the energy stored in the inductor?

A Lε/2R

B Lε2/2R2

C Lε2/2R

D Lε/2R2

E L2ε2/2R

Slide 13 / 25

13 An electric circuit consists of a battery of emf Ɛ, a resistor R and an inductor L. Which of the following represents the time constant?

A R/L

B RL

C ε/RL

D ε/L

E L/R

Slide 14 / 25

14 An electric circuit consists of a battery of emf Ɛ, a resistor R and an inductor L. The circuit has a time constant τ. When another identical resistor R is connected in parallel to the first one, what is the new time constant?

A τ

B 2τ

C 4τ

D τ /2

E τ /4

Slide 15 / 25

15 A resistor R, an inductor L and a battery Ɛ are connected in series. Which of the following represents the Kirchhoff’s loop rule for the given circuit?

A

B

C

D

E

Slide 16 / 25

16 In the circuit above, initially the switch is open and then it is closed at time t =0. What is the current in the resistor at this time?

A 3 A

B 1 A

C 0

D 0.5 A

E 0.3 A

Slide 17 / 25

17 In the circuit above, the switch has been closed for a long time, then it is reopened at time t =0. Which of the following graphs best represents the electric current i as a function of time t?

A B

CD

E

Slide 18 / 25

18 In the circuit above, the switch is closed for a long time. What is the energy stored in the inductor?

A 3 J

B 6 J

C 18 J

D 24 J

E 36 J

Slide 19 / 25

19 An inductor of inductance of 2 H is connected in series to a resistor of 10 Ω and a 12 V battery. What is the time constant of the circuit?

A 5 s

B 10 s

C 0.2 s

D 0.1 s

E 0.6 s

Slide 20 / 25

20 An inductor of inductance of 0.4 H is connected in series to a resistor of 6 Ω and a 12 V battery. What is the energy stored in the inductor?

A 0.8 J

B 1.2 J

C 1.8 J

D 2.4 J

E 3.2 J

Slide 21 / 25

21 In the circuit above, at time t=0 the switch is placed in the position A. What is the current in the resistor at this time?

A 0.3 A

B 0.6 A

C 0

D 3 A

E 6 A

Slide 22 / 25

22 In the circuit above, at time t=0 the switch is placed in the position A. What is the voltage across the resistor at this time?

A 3 V

B 6 V

C 9 V

D 12 V

E 0

Slide 23 / 25

23 In the circuit above, the switch has been kept at the position A for a long time and then at time t=0 is placed at the position B. What is the current in the resistor at this time?

A 0.3 A

B 0.6 A

C 0

D 3 A

E 6 A

Slide 24 / 25

24 In the circuit above, a fully charged capacitor with a capacitance C = 25 µF and charge Q = 4 µC is connected to an inductor L = 10 mH? What is the current in the circuit at the instant when the switch is closed?

A 1 A

B 5 A

C 0

D 10 A

E 15 A

Slide 25 / 25

25 In the circuit above, a fully charged capacitor with a capacitance C = 25 µF and charge Q = 4 µC is connected to an inductor L = 10 mH? Which of the following occurs after the switch is closed?

A The charge instantaneously decreases to zero

B The charge expotentially decreases to zero

C The charge stays unchanged

D The charge oscillate with a period of π ms

E The charge oscillate with a period of π μs