If a coil of $40$ turns and area $4 \, cm^2$ is suddenly removed from a magnetic field,it is observed that a charge of $2 \times 10^{-4} \, C$ flows through the coil. If the resistance of the coil is $80 \, \Omega$,the magnetic flux density in $Wb \, m^{-2}$ is:

Two coaxial coils carry current in the same direction. When the distance between the two coils is increased,the electric current in the coils will:

When two coaxial coils having the same current in the same direction are brought closer to each other,what happens to the value of the current in both coils?

Suppose a long solenoid of $100 \ cm$ length, radius $2 \ cm$ having $500 \ turns/cm$ carries a current $I = 10 \sin(\omega t) \ A$, where $\omega = 1000 \ rad/s$. $A$ circular conducting loop $(B)$ of radius $1 \ cm$ is coaxially placed inside the solenoid. The r.m.s. current through the loop when the coil $B$ is inside the solenoid is $\alpha / \sqrt{2} \ \mu A$. The value of $\alpha$ is . . . . . . . [Resistance of the loop $= 10 \ \Omega$]

$A$ copper ring having a cut such as not to form a complete loop is held horizontally and a bar magnet is dropped through the ring with its length along the axis of the ring as shown in figure. The acceleration of the falling magnet is ($g=$ acceleration due to gravity)

$A$ system $S$ consists of two coils $A$ and $B$. The coil $A$ carries a steady current $I$. The coil $B$ is suspended nearby as shown in the figure. If the system is heated,so as to raise the temperature of the two coils steadily,then: