Electromagnetic Induction and Alternating Currents

When a magnet is pushed into a coil, the work done against the magnetic repulsion is stored as:

If $1\text{ Weber} = 10^x\text{ Maxwell}$, then the value of $x$ is:

The CGS unit of magnetic flux is:

An induced EMF is produced when a magnet is moved relative to a coil. This EMF lasts:

A square loop of wire with side $L$ and resistance $R$ is moved with constant velocity $v$ into a uniform magnetic field $B$ as shown. The force required to keep the loop moving at constant velocity is:

Self-induction is sometimes called the 'inertia of electricity' because:

The flux linked with a coil is $0.8$ Wb. If it is reduced to $0.2$ Wb in $0.1$ s, the induced EMF is:

A copper wire is wound on a wooden frame. If the number of turns and the area of the cross-section are both doubled, the self-inductance becomes:

The energy stored in an inductor of inductance $L$ carrying current $I$ is $U$. If the current is doubled, the energy stored becomes:

A metal ring is held horizontally and a bar magnet is dropped through it. The flux through the ring is maximum when:

In a transformer, the principle of induction involved between the primary and secondary windings is:

The physical quantity which is measured in $Joules / Ampere^2$ is:

If a current of $1\ A$ flowing through a coil produces a magnetic flux linkage of $1\ Weber$ per turn, and the coil has $100$ turns, the self-inductance is:

The energy density (energy per unit volume) in the magnetic field of an inductor is proportional to:

If a coil of $100\text{ turns}$ is linked with a flux of $5 \times 10^{-4}\text{ Wb}$ when $2\text{ A}$ current flows, the self-inductance is:

When the current in a coil is $2\text{ A}$, the energy stored is $0.4\text{ J}$. If the current is increased to $4\text{ A}$, the energy stored will be:

What is the unit of the ratio of magnetic flux to current?

A metal ring is held horizontally and a bar magnet is dropped through the ring with its length along the axis of the ring. The acceleration of the falling magnet is:

The current in an $RL$ circuit drops from $I_0$ to $I_0/e$ in time $t$. The value of $t$ is:

Two coils are placed near each other. If the current in the first coil changes by $2\text{ A}$, the flux linkage in the second coil changes by $0.4\text{ Wb}$. The mutual inductance is:

The Sharpness of resonance in a series LCR circuit depends on:

If the capacitance in an LCR series circuit is doubled and the inductance is halved, the resonant frequency will:

Which component in an LCR circuit dissipates power?

The SI unit of Quality factor (Q-factor) of a resonant circuit is:

A series LCR circuit is connected to an AC source $V = V_0 \sin(\omega t)$. At resonance, the average power dissipated is:

In a series LCR circuit, the current lags behind the voltage by $\pi/4$ when:

An LCR circuit contains $L = 8.0 \, H, C = 0.5 \, \mu F$ and $R = 100 \, \Omega$ in series. The resonance angular frequency $\omega_r$ is:

In a series $LCR$ circuit, if $V_L = V_C = V_R$, the source voltage is $V$. The voltage across the inductor $V_L$ is:

Which of the following is true for an $LCR$ circuit at resonance?

A capacitor of $1\,\mu F$ and an inductor of $1\,mH$ are in an oscillating circuit. The maximum charge on the capacitor is $10\,\mu C$. The maximum current in the circuit is:

The principle of an AC generator is based on:

Which of the following describes a 'step-up' transformer?

In an AC generator, as the armature rotates through one full revolution, the direction of the induced current changes:

The unit of magnetic flux is:

The function of the brushes in an AC generator is to:

In a transformer, the primary voltage is $220 V$ and the primary current is $5 A$. If the secondary voltage is $55 V$ and the efficiency is $90\%$, what is the secondary current?

In an actual transformer, the efficiency is always less than $100\%$ because of:

A non-ideal transformer has a primary coil with self-inductance $L_p$ and a secondary coil with self-inductance $L_s$. The coefficient of coupling between the two coils is $k$ ($0 < k < 1$). If an alternating voltage $V_p = V_0 \sin(\omega t)$ is applied to the primary, the peak voltage $V_s$ induced across the secondary terminals in an open-circuit condition is given by:

Electrical power $P$ is transmitted from a power plant to a distant city through transmission lines of total resistance $R$. To minimize power loss, a step-up transformer with a turns ratio of $1:n$ (primary to secondary) is installed at the plant to increase the generation voltage $V$. Compared to transmitting the power at the original voltage $V$, the power loss in the transmission lines when using the transformer is reduced by a factor of:

An AC generator consists of a rectangular coil of $N$ turns and area $A$ rotating with a constant angular frequency $\omega$ in a uniform magnetic field $B$. The coil has a self-inductance $L$ and a total internal resistance $R$. If the terminals of the generator are short-circuited, what is the peak value of the induced current $I_0$ produced in the circuit?