A charged conductor produces an electric field of intensity $10^3 \mathrm{~V} / \mathrm{m}$ just outside its surface in vacuum. Then, it produces the electric field of intensity E just outside its surface, when it is placed in a medium of dielectric constant 4. The value of $E$ will be

In damped SHM, the SI unit of damping constant is

A wire of length $L$ and radius $r$ is rigidly fixed at one end. On stretching the other end of the wire with a force $F$, the increase in length is $I$. If another wire of the same material but double the length and radius is stretched with a force $2 F$, then increase in length is

When certain metal surface is illuminated with a light of wavelength $\lambda$, the stopping potential is $V$, When the same surface is illuminated by light of wavelength $2 \lambda$, the stopping potential is $\left(\frac{V}{3}\right)$. The threshold wavelength for the surface is