Unification of weak and electromagnetic interactions was done by

An electron moving with speed $v$ and a photon moving with speed $c$ have the same de Broglie wavelength. The ratio of the kinetic energy of the electron to that of the photon is -

In the following arrangement $y = 1.0\ mm$,$d = 0.24\ mm$ and $D = 1.2\ m$. The work function of the material of the emitter is $2.2\ eV$. The stopping potential $V_0$ needed to stop the photocurrent will be .............. $V$.

One day on a spacecraft corresponds to $2$ days on the earth. The speed of the spacecraft relative to the earth is

Dual nature of light is exhibited by

Match the following columns:

Column-$I$	Column-$II$
$A$. Hallwachs $\&$ Lenard	$P$. Transformers
$B$. Franck-Hertz	$Q$. Microwave
$C$. Klystron valve	$R$. Quantization of energy levels
$D$. Nicola Tesla	$S$. Photoelectric effect