An electron moves on a straight line path XY as shown in the figure. The coil abcd is adjacent to the path of the electron. What will be the direction of current, if any, induced in the coil?

(a)

The current will reverse its direction as the electron goes past the coil

(b)

No current will be induced

(c)

abcd

(d)

adcb

Electromagnetic induction is-not used in ___________________.

(a)

transformer

(b)

room heater

(c)

AC generator

(d)

choke coil

Lenz's law is in accordance with the law of ________________.

(a)

conservation of charges

(b)

conservation of flux

(c)

conservation of momentum

(d)

conservation of energy

Which of the following cannot be stepped up in a transformer?

(a)

input current

(b)

input voltage

(c)

input power

(d)

all

If a secondary coil has 40 turns, and a primary coil with 20 turns is charged with 50V of potential difference, then potential difference in secondary would be ________________.

(a)

50 V

(b)

25 V

(c)

60 V

(d)

100 V

In the following figure the key is dosed. Which statement is correct?

(a)

momentary current flows in Y circuit from B to A

(b)

momentary current flows in Y circuit from A to B

(c)

no current flows along AB

(d)

the coil Y is attracted to X

Which current- time graph represents the steady movement of short magnet through a coil XY?

(a)

(b)

(c)

(d)

The unit of self inductance is ________________.

(a)

Henry

(b)

Ampere

(c)

Farad

(d)

Ohm

The self inductance of a coil is ________________.

(a)

directly proportional to N

(b)

inversely proportional to N

(c)

directly proportional to N²

(d)

inversely proportional to N²

The self-inductance Lof a solenoid is given as _________________.

(a)

\(L=\frac { { \mu }_{ o }NA }{ l } \)

(b)

\(L=\frac { { \mu }_{ o }{ NA }^{ 2 } }{ l } \)

(c)

\(L=\frac { { \mu }_{ o }{ N }^{ 2 }A }{ l } \)

(d)

\(L=\frac { { { \mu }_{ o }A } }{ Nl } \)

The generator rule is ____________.

(a)

Fleming's left hand rule

(b)

Fleming's right hand rule

(c)

Maxwell's right hand cork screw rule

(d)

Right hand palm rule

Eddy currents was first observed by ________________.

(a)

Foucault

(b)

Newton

(c)

Faraday

(d)

Fleming

The property of a coil which enables to produce an opposite induced emf in it when the current in the coil changes is called _______________

(a)

electromagnetism

(b)

self - induction

(c)

mutual induction

(d)

parallel- induction

The necessary magnetic field for a low power a.c generator is produced by _________

(a)

electric coil

(b)

permanent magnets

(c)

electromagnets

(d)

batteries

In an a.c generator, the brushes are made of __________

(a)

silicon

(b)

plastic

(c)

carbon

(d)

nylon

__________ principle is used in transformer.

(a)

mutual induction

(b)

electromagnetic induction

(c)

self induction

(d)

eddy currents

A transformer is _____________.

(a)

converts energy

(b)

changes voltage

(c)

changes current

(d)

changes both current and voltage

The efficiency of an ideal transformer is ____________.

(a)

0

(b)

1

(c)

infinite

(d)

none

In an a.c. circuit with an inductor ______________.

(a)

voltage lags current by π/2

(b)

voltage and current are in phase

(c)

voltage leads current by π

(d)

current lags voltage by π/2

Inductive reactance, X_L = ?

(a)

2πnL

(b)

\(\frac { 2\pi v }{ L } \)

(c)

\(\frac { 2\pi }{ vL } \)

(d)

\(\frac { 2\pi }{ vL } \)

Unit of inductive reactance is ___________

(a)

ohm-metre

(b)

mho-metre^-1

(c)

ohm

(d)

mho

The unit of impedance is ________________

(a)

mho-metre^-1

(b)

ohm

(c)

ohm-metre

(d)

mho-metre

For normal frequencies, the range of Q- factor is from _____________.

(a)

1 to 10

(b)

10 to 100

(c)

100 to 1000

(d)

101 to 999

The Q factor of an a.c circuit containing a resistance R, inductance L and capacitor C is ________________.

(a)

\(Q=\frac { 1 }{ \sqrt { LC } } \)

(b)

\(Q=\frac { 1 }{ R } \sqrt { \frac { C }{ L } } \)

(c)

\(Q=\frac { 1 }{ R } \sqrt { \frac { L }{ C } } \)

(d)

\(Q=\frac { 1 }{ \sqrt { LR } } \)

The power factor of an a.c, circuit is _________

(a)

\(\phi \)sin\(\phi \)

(b)

cosec \(\phi \)

(c)

cos \(\phi \)

(d)

tan \(\phi \)