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

The flux linked with a coil at any instant t is given by \(\Phi\)_B = 10t² − 50t + 250. The induced emf at t = 3s is

(a)

−190 V

(b)

−10 V

(c)

10 V

(d)

190 V

In a transformer, the number of turns in the primary and the secondary are 410 and 1230 respectively. If the current in primary is 6A, then that in the secondary coil is

(a)

2 A

(b)

18 A

(c)

12 A

(d)

1 A

The instantaneous values of alternating current and voltage in a circuit are \(i=\frac { 1 }{ \sqrt { 2 } } \sin\left( 100\pi t \right) \) A and v \(=\frac { 1 }{ \sqrt { 2 } } \sin\left( 100\pi t+\frac { \pi }{ 3 } \right) V.\)The average power in watts consumed in the circuit is

(a)

\(\frac{1}{4}\)

(b)

\(\frac{\sqrt3}{4}\)

(c)

\(\frac{1}{2}\)

(d)

\(\frac{1}{8}\)

Electromagnetic induction is-not used in ___________________.

(a)

transformer

(b)

room heater

(c)

AC generator

(d)

choke coil

The unit henry can also be written as ______________.

(a)

VS A^-1

(b)

Wb A^-1

(c)

Ωs

(d)

all

An emf of 12V is induced when the current in the coil changes at the rate of 40 A S^-1. The coefficient of self induction of the coil is __________________.

(a)

0.3 H

(b)

0.003 H

(c)

30 H

(d)

4.8 H

Transformer works on _____________.

(a)

AC only

(b)

DC only

(c)

both AC and DC

(d)

AC more effectively than DC

The magnitude of the induced emf in a conductor depends on the _______________.

(a)

flux density of the magnetic field

(b)

amount of flux cut

(c)

amount of flux linkages

(d)

rate of change of flux

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

In Fleming's right hand rule, the forefinger represents the direction of ____________.

(a)

motion of the conductor

(b)

magnetic field

(c)

induced current

(d)

induced emf

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

(a)

electric coil

(b)

permanent magnets

(c)

electromagnets

(d)

batteries

A transformer is _____________.

(a)

converts energy

(b)

changes voltage

(c)

changes current

(d)

changes both current and voltage

Flux loss can be minimized using ________ core.

(a)

laminated

(b)

shell-type

(c)

perforated

(d)

sheet-type

An alternating current has _______________.

(a)

only positive value

(b)

only negative value

(c)

both positive and negative value

(d)

steady value

Inductive reactance, X_L = ?

(a)

2πnL

(b)

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

(c)

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

(d)

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

In LCR series circuit, at resonance is ___________

(a)

impedance (Z) is maximum

(b)

current is minimum

(c)

impedance (Z) is equal to R

(d)

v_o = \(\frac{1}{LC}\)

The average power consumed per cycle is ______________.

(a)

Zero

(b)

2000 W

(c)

1000 W

(d)

500 W

In RLC series AC circuit at resonance __________.

(a)

Resistance is zero

(b)

Net reactance is zero

(c)

impedance is maximum

(d)

voltage leads the current by a phase angle \(\frac{ㅠ}{2}\)