A circular coil has 100 turns, radius 3 cm and resistance $$4 \Omega$$. This coil is co-axial with a solenoid of 200 turns/$$\mathrm{cm}$$ and diameter 4 cm . If the solenoid current is decreased from 2 A to zero in 0.04 s , then the current induced in the coil is

The induced emf cannot be produced by

Assertion (A) When plane of coil is perpendicular to magnetic field, magnetic flux linked with the coil is minimum, but induced emf is zero.

Reason (R) $$\phi=n A B \cos \theta$$ and $$e=\frac{d \phi}{d t}$$

A solenoid of length $$60 \mathrm{~cm}$$ with 15 turns per $$\mathrm{cm}$$ and area of cross-section $$4 \times 10^{-3} \mathrm{~m}^2$$ completely surrounds another co-axial solenoid of same length and area of cross-section $$2 \times 10^{-3} \mathrm{~m}^2$$ with 40 turns per $$\mathrm{cm}$$. Mutual inductance of the system is