$A$ flat circular coil has $100$ turns of wire of radius $10 \ cm$. $A$ uniform magnetic field exists in a direction perpendicular to the plane of the coil and it grows at a rate of $0.1 \ T \ s^{-1}$. The induced emf in the coil is:

$A$ magnetic field of flux density $1.0 \,Wb \,m^{-2}$ acts normal to a $80$ turn coil of $0.01 \,m^2$ area. If this coil is removed from the field in $0.2 \,s$, then the emf induced in it is (in $\,V$)

$A$ coil is placed in a magnetic field $\vec{B}$ as shown below. $A$ current is induced in the coil because $\vec{B}$ is:

$A$ rectangular coil of $100$ turns and size $0.1 \,m \times 0.05 \,m$ is placed perpendicular to a magnetic field of $0.1 \,T$. If the field drops to $0.05 \,T$ in $0.05 \,s$, the magnitude of the e.m.f. induced in the coil is (in $\,V$)

$A$ square loop of wire,side length $10 \, cm$,is placed at an angle of $45^{\circ}$ with a magnetic field that changes uniformly from $0.1 \, T$ to zero in $0.7 \, s$. The induced current in the loop (its resistance is $1 \, \Omega$) is ..... $mA$.

It is desired to measure the magnitude of the magnetic field between the poles of a powerful loudspeaker magnet. $A$ small flat search coil of area $2 \; cm^{2}$ with $25$ closely wound turns is positioned normal to the field direction and then quickly snatched out of the field region. (Equivalently,one can give it a quick $90^{\circ}$ turn to bring its plane parallel to the field direction). The total charge flown in the coil (measured by a ballistic galvanometer connected to the coil) is $7.5 \; mC$. The combined resistance of the coil and the galvanometer is $0.50 \; \Omega$. Estimate the field strength of the magnet.