A beaker is filled with water (refractive index $\frac{4}{3}$ ) up to a height $H$. A coin is placed at its bottom. The depth of the coin, when viewed along the near ${ }^n$ ormal direction, will be

The stopping potential $V_0$ measured in a photoelectric experiment for a metal surface is plotted against frequency $v$ of the incident radiation. Let $m$ be the slope of the straight line so obtained. Then the value of charge of an electron is given by ( $h$ is the Planck's constant)

Let $\lambda_{e r} \lambda_p$ and $\lambda_d$ be the wavelengths associated with an electron, a proton and a deuteron, all moving with the same speed. Then the correct relation between them is

Which of the following figures correctly represents the shape of curve of binding energy per nucleon as a function of mass number?