Electromagnetic Induction MCQs | Physics MCQs

The output of a simple AC generator is a voltage that varies as a:

The key difference in construction between a DC generator and an AC generator is the use of a:

A transformer is used to change:

Two coils have a mutual inductance of 0.5 H. If the current in the primary coil changes at a rate of 8 A/s, what is the magnitude of the induced EMF in the secondary coil?

In a step-up transformer:

For an ideal transformer, the relationship between voltages (V) and the number of turns (N) is given by:

How much energy is stored in the magnetic field of an 8.0 H inductor when a current of 5.0 A is flowing through it?

If a transformer steps up the voltage, it will:

Eddy currents are loops of electric current induced within conductors by a:

Which of the following is an application of eddy currents?

The RMS voltage of the AC supply in Pakistan is 230 V. What is the peak voltage?

To minimize energy loss due to eddy currents, the iron core of a transformer is:

Faraday's law of induction states that the induced EMF is proportional to the:

If the number of turns in a coil is doubled, while other factors remain constant, the induced EMF will:

A north pole of a magnet is moved towards a conducting loop. The direction of the induced current in the loop will be such that the face of the loop towards the magnet becomes a:

An inductor of 50 mH has its current drop from 4 A to 0 A in 0.01 s. What is the magnitude of the self-induced EMF?

Energy stored in an inductor is stored in the form of:

Two coils are placed close to each other. The mutual inductance between the coils depends on:

In an AC generator, the frequency of the output voltage in Pakistan is typically:

A transformer has a primary coil with 200 turns and a secondary coil with 50 turns. If the primary voltage is 240 V AC, the secondary voltage will be:

The core of a transformer is laminated to reduce:

Why does a transformer not work with DC?

An ideal transformer has an efficiency of:

In a generator, the induced current in the rotating coil is always:

Motional EMF is a consequence of which force acting on the charge carriers inside the conductor?

If the rate of change of current in a coil of self-inductance 2 H is 5 A/s, the induced EMF is:

Which of the following does NOT affect the mutual inductance of two coils?

In electromagnetic damping, eddy currents are induced to:

An inductor of 1 H carries a current of 2 A. The energy stored in its magnetic field is:

The working principle of a DC motor is based on the fact that a current-carrying conductor in a magnetic field experiences a:

A step-down transformer has a turn ratio of 10:1. If the input current is 2 A, what is the output current, assuming it's an ideal transformer?

What is the purpose of the soft iron core in a generator or motor?

When a DC motor is first switched on, the back EMF is:

The total magnetic flux through a closed surface is always:

A metal detector works on the principle of:

If the speed of rotation of an AC generator's coil is doubled, the output frequency will:

A conductor of length 2.0 m moves at 5.0 m/s at an angle of 30° to a uniform magnetic field of 0.4 T. The induced EMF is:

In the context of power transmission, high voltage is used to:

The negative sign in Faraday's law of induction, ε = -N(dΦ/dt), represents:

An inductor resists the flow of DC current because of its:

If the magnetic field through a stationary loop of wire is uniform and constant, the induced EMF is:

A transformer with 500 primary turns and 2500 secondary turns is connected to a 200 V AC supply. The peak voltage across the secondary coil is approximately:

The coefficient of mutual inductance is numerically equal to the induced EMF in the secondary coil when the rate of change of current in the primary coil is:

A metal ring is dropped vertically through a horizontal magnetic field. The acceleration of the ring is:

Hysteresis loss in a transformer core is caused by:

Which material is preferred for the core of a transformer to minimize hysteresis loss?

A coil with 100 turns experiences a change in magnetic flux from 2.0 Wb to 8.0 Wb in 3.0 seconds. What is the magnitude of the average induced EMF in the coil?

The back EMF in a DC motor is greatest when the motor is:

A solenoid has an inductance of 5 H. If the current through it changes from 2 A to 4 A in 0.1 s, the average induced EMF is:

In an LC circuit, when the energy stored in the inductor's magnetic field is maximum, the energy stored in the capacitor's electric field is:

The phase difference between the voltage and current in a purely inductive AC circuit is:

An AC generator produces a peak voltage of 340 V. What is the approximate RMS voltage?

One Weber is equivalent to:

What is the magnetic flux through a rectangular loop of area 0.5 m² if the magnetic field of 2.0 T makes an angle of 60° with the normal to the plane of the loop?

The phenomenon used in electromagnetic braking is:

A conducting loop is held stationary in a non-uniform magnetic field that is increasing in strength. An EMF is induced in the loop because:

The turns ratio of a transformer is 1:4. If a 12 V DC source is connected to the primary, the voltage across the secondary will be:

Which of the following is NOT a unit of inductance?

To increase the angular speed of a DC motor, you should:

A 'choke coil' is a simple inductor used to control current in an AC circuit with minimal power loss. This is because an ideal choke has:

The quantity that remains unchanged in an ideal transformer is:

If you cut a bar magnet in half, you will have:

A generator produces a peak EMF of 120 V. The RMS value of the EMF is:

The energy density (energy per unit volume) of a magnetic field B in a solenoid is proportional to:

An ideal transformer has 400 turns on the primary coil and 1200 turns on the secondary. If the primary voltage is 110 V AC, what is the secondary voltage?

In an AC generator, slip rings are used to:

An airplane is flying horizontally over the magnetic north pole, where the Earth's magnetic field is directed vertically. The potential difference induced between its wingtips will be:

A simple pendulum with a metallic bob is oscillating in a uniform magnetic field directed perpendicular to its plane of oscillation. The oscillations will be:

The time constant (τ) of an RL circuit is given by:

If the current in the primary coil of a transformer is suddenly switched off, a large EMF is induced in the secondary coil. This is the principle behind:

The time constant of an RL circuit is 0.02 s. If the inductance is 200 mH, what is the resistance?

Two parallel wires carry currents in the same direction. The force between them is:

A magnetic compass is placed near a coil. When a current is passed through the coil, the compass needle deflects. This demonstrates that:

In a region where the magnetic field is zero, can an induced EMF be produced in a coil?

A 100% efficient step-down transformer has 200 turns on the primary and 50 turns on the secondary. If the primary current is 3 A, the secondary current is:

The direction of the induced current in a conductor moving in a magnetic field is such that the magnetic force on the conductor:

The operation of a Ground Fault Circuit Interrupter (GFCI) is based on:

An AC generator produces a maximum EMF of 170 V. What is the instantaneous EMF when the coil makes an angle of 45° with the magnetic flux?

A jet of conducting liquid is shot through the poles of a strong magnet. A potential difference will be induced:

An inductor of 50 mH has its current drop from 4 A to 0 A in 0.01 s. What is the magnitude of the self-induced EMF?

What is the instantaneous EMF produced by an AC generator when its coil makes an angle of 30 degrees with the magnetic flux, if the maximum EMF is ε₀?

If you increase the frequency of the AC supply to a transformer, what happens to the mutual inductance?

The role of a capacitor in a traditional DC motor is often to:

A long straight wire carries a current that is increasing with time. A circular conducting loop is placed next to the wire in the same plane. The induced current in the loop will be:

A 'search coil' is used to measure magnetic fields by being rapidly removed from the field. The induced ______ is measured.

Which of the following is a non-conservative field?

When a magnet is broken into two pieces:

The power factor in a purely inductive or purely capacitive circuit is:

The self-inductance of a coil is a measure of its ability to:

An ideal step-up transformer increases the:

A straight conductor of length 0.5 m is moved with a speed of 10 m/s at an angle of 30 degrees to a magnetic field of 0.8 T. The induced EMF is:

Cores of electromagnets are made of ferromagnetic materials like soft iron to provide:

The process of generating electricity in a modern power plant most closely relies on the discoveries of:

An inductor blocks AC but allows DC to pass. Why?

If you double the number of turns and the length of a long solenoid while keeping the area constant, its self-inductance will be:

A small, permanent magnet is pushed into a coil and then pulled out at the same speed. The induced current will be: