The photoelectric effect shows:

Electrons are emitted with zero velocity from a metal surface when it is exposed to radiation of wavelength $8000 \ \mathring{A}$. What should be the maximum velocity of emitted electron when the same metal surface is exposed to radiation of wavelength $5000 \ \mathring{A}$? $\left( h = 6.6 \times 10^{-34} \ J \cdot s, \ m_e = 9.1 \times 10^{-31} \ kg, \ c = 3 \times 10^8 \ m/s \right)$

In the visible spectrum,which color,violet or red,undergoes greater refraction? Why?

The photoelectric effect is described as the ejection of electrons from the surface of a metal when :

Match the following:

List-$I$	List-$II$
$(1)$ $X$-rays	$(A)$ $\nu = 10^0 - 10^4 \ Hz$
$(2)$ Ultraviolet $(UV)$ rays	$(B)$ $\nu = 10^{10} \ Hz$
$(3)$ Long radio waves	$(C)$ $\nu = 10^{16} \ Hz$
$(4)$ Microwave	$(D)$ $\nu = 10^{18} \ Hz$

Work functions of four metals $M_1, M_2, M_3$ and $M_4$ are $4.8, 4.3, 4.75$ and $3.75 \ eV$ respectively. The metals which do not show photoelectric effect when light of wavelength $310 \ nm$ falls on the metals are