The magnetic field (B) inside a long solenoid having ' $n$ ' turns per unit length and carrying current ' i ' when iron core is kept in it, is ( $\mu_0=$ permeability of vacuum, $\chi=$ magnetic susceptibility)

A gas having $\gamma=\frac{5}{2}$ and volume 360 c.c. is suddenly compressed to 90 c.c. If the initial pressure of the gas is P , then the final pressure will be

In Young's double slit experiment, the intensity on screen at a point, where path difference is $\frac{\lambda}{4}$ is $\frac{K}{4}$. The intensity at a point when path difference is ' $\lambda$ ' will be $\left[\cos \frac{\pi}{2}=0, \cos 2 \pi=1\right]$

When LED is manufactured by using aluminium gallium arsenide (AlGaAs), it emits