$A$ magnetic field $4 \times 10^{-2} \, T$ acts at right angles to a coil of area $100 \, cm^2$ with $50$ turns. The average e.m.f. induced in the coil is $0.1 \, V$, when it is removed from the field in time '$t$'. The value of '$t$' is

An insulated copper wire of $100$ turns is wrapped around a wooden cylindrical core of the cross-sectional area $24\,cm^2$. The two ends of the wire are connected to a resistor. The total resistance in the circuit is $12\,\Omega$. If an externally applied uniform magnetic field in the core along its axis changes from $1.5\,T$ in one direction to $1.5\,T$ in the opposite direction,the charge flowing through a point in the circuit during the change of magnetic field will be $.........\,mC$.

$A$ long solenoid with $15$ turns per $cm$ has a small loop of area $2.0 \; cm^{2}$ placed inside the solenoid normal to its axis. If the current carried by the solenoid changes steadily from $2.0 \; A$ to $4.0 \; A$ in $0.1 \; s$, what is the induced $emf$ in the loop while the current is changing?

State and explain Faraday's law of electromagnetic induction.

$A$ flexible circular loop $20 \ cm$ in diameter lies in a magnetic field of magnitude $B = 1 \ T$,directed into the plane of the page as shown. The loop is pulled at the points indicated by the arrows,forming a loop of zero area in $0.314 \ s$. The average emf induced in the loop is.....$V$

$A$ 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: