Mix Test

Question 1
1 / -0

Which of the following statement is correct regarding AC generators?

A
It converts mechanical energy into electrical energy.

B
It works on the principle of Faraday's Law.

C
Generated energy can be in the form of sinusoidal waveform.

D
All of the above statements are correct regarding AC generators.

Question 2
1 / -0

Initially, an LC circuit is open and the charge on the capacitor is \(2 \times 10^{-5} \mathrm{C}\). If the natural frequency of the circuit is \(4 \times 10^{3} \mathrm{rad} / \mathrm{sec}\), then find the maximum current flowing through the circuit when the circuit is closed.

A
\(8 \times 10^{-2} \mathrm{~A}\)

B
\(\sqrt{8} \times 10^{-1} \mathrm{~A}\)

C
\(2 \mathrm{~A}\)

D
None of these

Question 3
1 / -0

When a bar magnet is moved axially towards a coil, then which of the following is correct:

A
Emf must be induced but current may or may not get induced in the coil

B
Both emf and current will get induced in the coil

C
No emf or current will get induced in the coil

D
None of these

Question 4
1 / -0

In a AC circuit \(\mathrm{R}=0 \Omega, \mathrm{X}_{\mathrm{L}}=8 \Omega\) and \(\mathrm{X}_{\mathrm{C}}=6 \Omega\) phase difference between voltage and current is:

A
\(110^{\circ}\)

B
\(90^{\circ}\)

C
\(37^{\circ}\)

D
\(12^{\circ}\)

Question 5
1 / -0

In the series LCR circuit, the power dissipation is through:

A
R

B
L

C
C

D
Both l and C

Question 6
1 / -0

The current in an inductor of inductance 100 mH is dropped from 4 A to 0 A.
The time required to induce 5V across the inductor is______.

A
8 s

B
0.08 s

C
4 s

D
1 s

Question 7
1 / -0

The value of alternating emf E in the given circuit will be:

A
220 V

B
140 V

C
100 V

D
20 V

Question 8
1 / -0

The magnetic flux in a coil changes from \(20 \times 10^{-2}\) Weber to \(12 \times 10^{-2}\) Weber in \(0.02\) s. Find the value of induced emf in the coil.

A
4 V

B
0.4 V

C
16 V

D
0.16 V

Question 9
1 / -0

Two long solenoids \(S_{1}\) and \(S_{2}\) have equal lengths and the solenoid \(S_{1}\) is placed co-axially inside the solenoid \(S_{2}\). This pair of solenoids have a mutual inductance of \(200\) H. The number of turns in solenoid \(S_{1}\) and \(S_{2}\) are \(100\) and \(120\) respectively. If the current in the outer solenoid is \(5\) A, then the flux linkage with the inner solenoid is:

A
5 Wb

B
10 Wb

C
20 Wb

D
None of these

Question 10
1 / -0

The magnetic field and number of turns of the coil of an electric generator is doubled then the magnetic flux of the coil will:

A
Become half

B
Become two times

C
Become three times

D
Become four times

Question 11
1 / -0

Two solenoids S1 and S2 have equal lengths of 2 m and the solenoid S1 is placed co-axially inside the solenoid S2. The number of turns per unit length of both the solenoids is 100 . The radius of the solenoid S1 and S2 is 7 cm and 14 cm respectively, then find the mutual inductance:

A
9.68×10−5 H

B
8.48×10−5 H

C
9.68×10−7 H

D
None of these

Question 12
1 / -0

A coil of inductive reactance \(31 \Omega\) has a resistance of \(8 \Omega\). It is placed in series with a condenser of capacitance reactance \(25 \Omega\). The combination is connected to an AC source of \(110 \mathrm{~V}\). The power factor of the circuit is:

A
0.4

B
0.64

C
0.8

D
1.6

Question 13
1 / -0

When the north pole of a magnet is moved towards a coil that is connected to a circuit, consider the following statement:
a. North pole will be formed on the magnet side of the coil.
b. South pole will be formed on the magnet side of the coil.
c. Direction of Induced current will be clockwise when the coil is seen from the magnet side.
d. Direction of Induced current will be anti clockwise when the coil is seen from the magnet side.

A
Both a and c are correct

B
Both a and d are correct

C
Both b and c are correct

D
Both b and d are correct

Question 14
1 / -0

In a series, L.C.R circuit an alternating emf (v) and current (i) are given by the equation \(v=v_{0}\) \(\sin (\omega \mathrm{t}), i=i_{0} \sin \left(\omega t+\frac{\pi}{3}\right)\). The average power dissipated in the circuit over a cycle of AC is:

A
\(\frac{v_{0} i_{0}}{2}\)

B
\(\frac{v_{0} i_{0}}{4}\)

C
\(\frac{\sqrt{3}}{2} v_{0} i_{0}\)

D
Zero

Question 15
1 / -0

In the second experiment of Faraday and Henry, the primary coil is connected to the galvanometer and the secondary coil is connected to a battery. If the primary coil is rotated about its axis, then:

A
The current will induce in the primary coil

B
No current will induce in the primary coil

C
Momentary current will induce in the primary coil

D
Can't say

Question 16
1 / -0

A rectangular coil of one turn and size \(1 \mathrm{~m} \times 0.5 \mathrm{~m}\) is placed perpendicular to a magnetic field of \(1 \mathrm{~T}\). If the field drops to \(0.5 \mathrm{~T}\), find the change in magnetic flux generated in the rectangular coil.

A
2.5 Wb

B
0.25 Wb

C
0.5 Wb

D
0.1 Wb

Question 17
1 / -0

During the magnetic braking of trains if the north and the south poles are replaced with each other, then the velocity of the train will:

A
Increase

B
Decrease

C
Remain unchanged

D
Can't say

Question 18
1 / -0

A coil of wire of radius R has 200 turns and self – inductance of 108 mH. The self – inductance of a similar coil of 500 turns will be:

A
375 mH

B
527 mH

C
675 mH

D
None of these

Question 19
1 / -0

Two long solenoids \(S_{1}\) and \(S_{2}\) have equal lengths and the solenoid \(S_{1}\) is placed co-axially inside the solenoid \(S_{2}\). If the current in both the solenoids is doubled, then the mutual inductance of both the solenoids will become:

A
Four times

B
Double

C
Remain unchanged

D
None of these

Question 20
1 / -0

A boy is pedaling a stationary bicycle that is attached to a coil of area \(0.7 \mathrm{~m}^{2}\). The coil consists of 100 turns. The coil is rotating at the rate of 60 revolutions per minute and placed in a uniform magnetic field of \(0.02 \mathrm{~T}\). The field is perpendicular to the axis of rotation of the coil. Find the maximum emf generated in the coil.

A
8.8 volt

B
7.6 volt

C
9.8 volt

D
None of these

Question 21
1 / -0

Find the angular frequency of the oscillation for the circuit shown in the figure:

A
\(5 \times 10^{3} \mathrm{rad} / \mathrm{sec}\)

B
\(20 \times 10^{3} \mathrm{rad} / \mathrm{sec}\)

C
\(25 \times 10^{3} \mathrm{rad} / \mathrm{sec}\)

D
None of these

Question 22
1 / -0

An ideal transformer has 500 and the 1000 turns in the primary and the secondary coil. If the DC voltage of 120 V is applied to the primary coil, then the emf produced at the secondary coil will be:

A
60 V

B
240 V

C
30 V

D
Zero

Question 23
1 / -0

A magnet NS is suspended from a spring and while it oscillates, the magnet moves in and out of the coil. The coil is connected to a galvanometer G. Then, as the magnet oscillates,

A
G shows deflection to the left and right with constant amplitude.

B
G shows deflection on one side.

C
G shows no deflection.

D
G shows deflection to the left and right but the amplitude steadily decreases.

Question 24
1 / -0

An ideal transformer has 100 turns in the primary and 250 turns in the secondary. The peak value of the ac is 28 V. The r.m.s. secondary voltage is nearest to:

A
50 V

B
70 V

C
100 V

D
40 V

Question 25
1 / -0

If the north pole of a magnet is moved away from a coil which is connected in a closed circuit, then the direction of current in the coil on the magnet side will be:

A
Clockwise

B
Anti clockwise

C
No current will flow in the coil

D
Can't say

Question 26
1 / -0

In the given figure a metallic plate A is allowed to swing like a simple pendulum between the magnetic poles and it comes to rest after time t. If a slot is cut in the plate A and then it is allowed to swing with the same initial velocity as before then the time taken by it to come to rest will be:

A
More than t

B
Less than t

C
t

D
Can't say

Question 27
1 / -0

A 220-volt input is supplied to a transformer. The output circuit draws a current of 2.0 ampere at 440 volts. If the efficiency of the transformer is 80%, the current drawn by the primary windings of the transformer is:

A
5.0 ampere

B
3.6 ampere

C
2.8 ampere

D
2.5 ampere

Question 28
1 / -0

\(5.5 \times 10^{-4}\) magnetic flux lines are passing through a coil of resistance \(10\) ohm and number of turns 1000. If the number of flux lines reduces to \(5 \times 10^{-5}\) in \(0.1\) sec, find the current induced in the coil.

A
0.25 A

B
0.5 A

C
1.00 A

D
1.5 A

Question 29
1 / -0

An AC generator consists of a coil of 800 turns and a cross-sectional area of \(2.5 \mathrm{~m}^{2}\). The coil is placed in a uniform magnetic field of \(0.05 \mathrm{~T}\) and it is rotated with an angular speed of 50 \(\mathrm{rad} / \mathrm{sec}\). If the resistance of the coil is \(200 \Omega\), then find the maximum current produced by the generator:

A
\(25 \mathrm{~A}\)

B
\(50 \mathrm{~A}\)

C
\(20 \mathrm{~A}\)

D
None of these

Question 30
1 / -0

An LCR circuit is connected to AC voltage source of emf E. The equation for power dissipated in this circuit is:

A
\(\frac{E R}{\sqrt{R^{2}+\left(L w-\frac{1}{C w}\right)^{2}}}\)

B
\(\frac{E^{2}\left[R^{2}+\left(L w-\frac{1}{C w}\right)^{2}\right]}{R}\)

C
\(\frac{E^{2} R}{\left[R^{2}+\left(L w-\frac{1}{C w}\right)^{2}\right]}\)

D
\(\frac{E^{2} \sqrt{R^{2}+\left(L w-\frac{1}{C w}\right)^{2}}}{R}\)

Submit Test

Mix Test - 4...

Question 1

It converts mechanical energy into electrical energy.

It works on the principle of Faraday's Law.

Generated energy can be in the form of sinusoidal waveform.

All of the above statements are correct regarding AC generators.

Question 2

\(8 \times 10^{-2} \mathrm{~A}\)

\(\sqrt{8} \times 10^{-1} \mathrm{~A}\)

\(2 \mathrm{~A}\)

None of these

Question 3

Emf must be induced but current may or may not get induced in the coil

Both emf and current will get induced in the coil

No emf or current will get induced in the coil

None of these

Question 4

\(110^{\circ}\)

\(90^{\circ}\)

\(37^{\circ}\)

\(12^{\circ}\)

Question 5

R

L

C

Both l and C

Question 6

8 s

0.08 s

4 s

1 s

Question 7

220 V

140 V

100 V

20 V

Question 8

4 V

0.4 V

16 V

0.16 V

Question 9

5 Wb

10 Wb

20 Wb

None of these

Question 10

Become half

Become two times

Become three times

Become four times

Question 11

9.68×10−5 H

8.48×10−5 H

9.68×10−7 H

None of these

Question 12

0.4

0.64

0.8

1.6

Question 13

Both a and c are correct

Both a and d are correct

Both b and c are correct

Both b and d are correct

Question 14

\(\frac{v_{0} i_{0}}{2}\)

\(\frac{v_{0} i_{0}}{4}\)

\(\frac{\sqrt{3}}{2} v_{0} i_{0}\)

Zero

Question 15

The current will induce in the primary coil

No current will induce in the primary coil

Momentary current will induce in the primary coil

Can't say

Question 16

2.5 Wb

0.25 Wb

0.5 Wb