The Lenz law is associated with

Magnetic flux linked with the coil is given by $\phi(t) = 2t^2 + 2t + 1$ and its resistance is $10 \ \Omega$. The current passing through the coil at $t = 2 \ s$ is . . . . . . $A$.

Two identical circular loops of metal wire are lying on a table without touching each other. $Loop-A$ carries a current which increases with time. In response,the $loop-B$

$A$ long solenoid having $100$ turns per $cm$ carries a current of $\frac{4}{\pi} \,A$. At the centre of it is placed a coil of $200$ turns of cross-sectional area $25 \,cm^2$ having its axis parallel to the field produced by the solenoid. When the direction of the current in the solenoid is reversed within $0.04 \,s$, the induced emf in the coil is (in $\,V$)

$A$ circular loop of flexible conducting material is kept in a magnetic field directed perpendicularly into its plane. By holding the loop at diametrically opposite points,it is suddenly stretched outwards,then

Assertion $(A)$: When a circular coil,placed in a region with its plane parallel to a magnetic field,expands radially outwards,no emf is induced in it.
Reason $(R)$: There is a constant magnetic field in the perpendicular (to the plane of the coil) direction.