The magnetic flux through a circuit of resistance $R$ changes by an amount $\Delta \phi$ in the time $\Delta t$. The total quantity of electric charge $Q$ which passes during this time through any point of the circuit is

$A$ square wire loop of side $10.0 \, cm$ is placed in a uniform perpendicular magnetic field of $20 \, T.$ The magnetic field decreases to zero in time interval $\Delta t.$ The bulb will glow with full brightness if the value of $\Delta t$ is.....$ms.$ (Assume the bulb requires $10 \, V$ to glow with full brightness.)

$A$ long solenoid of radius $2\, cm$ has $100\, turns/cm$ and carries a current of $5\, A$. $A$ coil of radius $1\, cm$ having $100\, turns$ and a total resistance of $20\, \Omega$ is placed inside the solenoid coaxially. The coil is connected to a galvanometer. If the current in the solenoid is reversed in direction,find the charge flown through the galvanometer.

$A$ loop of irregular shape of conducting wire (as shown in the figure) is placed in a uniform magnetic field perpendicular to the plane of the paper. If the loop changes into a circular shape,the direction of the induced current will be:

Discuss Faraday's experiment which shows that relative motion is not an absolute requirement for electromagnetic induction.

$A$ coil having $200$ turns has a surface area of $0.15 \ m^2$. $A$ magnetic field of strength $0.2 \ T$ applied perpendicular to this changes to $0.6 \ T$ in $0.4 \ s$,then the induced emf in the coil is . . . . . . $V$.