Electromagnetic Induction Test

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Electromagnetic Induction Test - 3

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Question 1
1 / -0

Two parallel wires PQ and ST, placed a distance w apart, are connected by a resistor R as shown in the figure and placed in a magnetic field B which is perpendicular to the plane containing the wires. A rod CD connects the two wires. The power spent to slide the rod CD with a velocity v along the wires is (neglect the resistance of the wires and that of the rod)

A

B

C

D
Question 2
1 / -0

As a result of change in magnetic flux linked to a closed loop as shown in the figure, an emf of V volt is induced in the loop. The work done (in joules) in taking a charge Q coulomb once along the loop is

A
QV

B
0

C
2QV

D
Question 3
1 / -0

A coil of metal wire is kept stationary with its plane perpendicular to a uniform magnetic field directed along the positive x-axis. The current induced in the coil

A
circulates in anti-clockwise direction when viewed from the x-axis

B
circulates in clockwise direction when viewed from the x-axis

C
is perpendicular to the direction of the magnetic field

D
is zero
Question 4
1 / -0

Two circular coils can be arranged in any of the three orientations shown below. Their mutual inductance will be

A
maximum in situation (A)

B
maximum in situation (B)

C
maximum in situation (C)

D
the same in all the situations
Question 5
1 / -0

When current carrying coil C₂ is moved towards the coil C₁ connected in series with a galvanometer, the pointer in the galvanometer G

A
shows deflection while C₂ is in motion .

B
oscillates

C
does not move

D
shows deflection while C₂C₂ is stationary

Solution

current induced due to flux changed when C₂ is in motion.
Question 6
1 / -0

A wireloop of radius R confined in a plane is rotated in its plane with some angular velocity . A uniform magnetic field exists in the region. The emf induced is

A
Br²

B
zero

C

D
2Br²
Question 7
1 / -0

When a bar magnet is pushed towards the coil connected in series with a galvanometer, the pointer in the galvanometer G

A
oscillates

B
shows deflection while bar is stationary

C
does not move

D
shows deflection while bar is in motion

Solution

When bar is in motion then flux will changed hence current will be induced.
Question 8
1 / -0

The figure below shows two coils placed close to each other. When the key K is pressed, a current starts building up in one of the coils. Then,

A
current flows along ABC in the other coil

B
current flows along CBA in the other coil

C
no current flows in the other coil

D
an alternating current flows in the other coil
Question 9
1 / -0

The figure below shows two coils placed close to each other. When the current through one coil is decreased gradually by shifting the position of the rheostat, then

A
current flows along ABC in the other coil

B
current flows along CBA in the other coil

C
no current flows in the other coil

D
an alternating current flows in the other coil
Question 10
1 / -0

An airplane, with 20 m wingspread, is flying at 250 ms^-1 parallel to the Earth's surface at a place where the horizontal component of Earth's magnetic field is 2 10^-5 T and angle of dip is 60°. The magnitude of the induced emf between the tips of the wings is

A

B

C

D
Question 11
1 / -0

A circular loop of radius R, carrying current I, lies in xy-plane with its centre at origin. The total magnetic flux through xy-plane is

A
directly proportional to R

B
directly proportional to I

C
inversely proportional to I

D
zero
Question 12
1 / -0

A metallic wheel with 8 metallic spokes, each of length r, is rotating at an angular frequency w in a plane perpendicular to a magnetic field B. The magnitude of the induced emf between the axle and the rim of the wheel is

A

B

C

D
Question 13
1 / -0

A rectangular coil of copper wires is rotated in a magnetic field. The direction of the induced current changes once in each

A
two revolutions

B
one revolution

C
half revolution

D
one-fourth revolution
Question 14
1 / -0

electromagnetic induction i.e currents can be induced in coils (Select the best)

A
Only if the coil moves and magnet also moves in the same direction

B
Only if the magnet moves

C
if relative motion of coil and magnet is present.

D
Only if the coil moves

Solution

for electromagnetic induction magnet and coil both may move but relative motion between must be present
Question 15
1 / -0

Coils C₁ and C₂ are stationary. C₁ connected in series with one very small Diwali bulb while C2 is connected to a battery. If the connection is suddenly snapped

A
the bulb absorbs light

B
the bulb keeps glowing

C
nothing happens to the bulb

D
the bulb glows momentarily.

Solution

Flux will be changed due to this current is induced momentarily
Question 16
1 / -0

In a car spark coil, an emf of 40000 volts is induced in its secondary winding when the current in its primary winding changes from 4 A to zero in 10 s. The mutual inductance between the primary and the secondary windings of the spark coil is

A
0.1 H

B
0.3 H

C
0.2 H

D
0.4 H
Question 17
1 / -0

Calculate magnetic flux density of the magnetic field at the centre of a circular coil of 50 turns, having a radius of \(0.5 \mathrm{~m}\) and carrying a current of 5 A.

A
\(2.14 \times 10^{-4} \mathrm{~T}\)

B
\(3.11 \times 10^{-4} \mathrm{~T}\)

C
\(3.14 \times 10^{-4} \mathrm{~T}\)

D
\(3.14 \times 10^{-5} \mathrm{~T}\)

Solution

\(\mathrm{N}=50\) turns, Radius \(\mathrm{r}=0.5 \mathrm{~m},\) Current \(\mathrm{I}=5 \mathrm{~A}\)
\(\therefore\) Magnetic flux density at centre \(=\mathrm{B}=\frac{\mu_{0} N I}{2 a}\)
\(=\frac{4 \pi \times 10^{-7} \times 50 \times 5}{2 \times 0.5} T\)
\(=2 \pi \times 10^{-7} \times 500 T\)
\(B=3.14 \times 10^{-4} \mathrm{~T}\)
Hence, the correct option is (C).
Question 18
1 / -0

The dimensional equation for magnetic flux is:

A
\({ML}^{2} {~T}^{-2} {I}^{-1}\)

B
\({ML}^{2} {~T}^{-2} {I}^{-2}\)

C
\({ML}^{-2} {~T}^{-2} {I}^{-1}\)

D
\({ML}^{2} {~T}^{-2} {I}^{2}\)

Solution

Magnetic flux \(=\) Magnetic Field \((B) ×\) Area \((A)\)
\(B\)'s dimensions \(={Tesla}={MI}^{-1} {~T}^{-2}\)
\(A\)'s dimensions \(={L}^{2}\)
Therefore, \({BA}={ML}^{2} {~T}^{-2} {I}^{-1}\)
Hence, the correct option is (A).
Question 19
1 / -0

What is the self-inductance of an air-core solenoid of length 3.14 m and cross-sectional area 10^–3 m² with 500 turns?

A
0.1 mH

B
0.2 mH

C
0.3 mH

D
0.4 mH
Question 20
1 / -0

According to Faraday's law

A
The magnitude of the induced emf in a circuit is equal to the time rate of change of magnetic flux through the circuit. .

B
The magnitude of the induced emf in a circuit is equal to the time of change of magnetic flux through the circuit.

C
The magnitude of the induced emf in a circuit is equal to the time of change of magnetic flux through the circuit.

D
The magnitude of the induced emf in a circuit is proportional to the time of change of magnetic flux through the circuit.

Solution

The induced electromotive force in any closed circuit is equal to the negative of the time rate of change of the magnetic flux enclosed by the circuit.