When light of frequency v₁ is incident on a metal with work function W (where hv₁ > W), then photocurrent falls to zero at a stopping potential of V₁. If the frequency of light is increased to v₂, the stopping potential changes to V₂. Therefore, the charge of an electron is given by

The potential difference V required for accelerating an electron to have the de-Broglie wavelength of 1 $$\mathop A\limits^o $$ is

The work function of Cesium is 2.27 eV. The cut-off voltage which stops the emission of electrons from a cesium cathode irradiated with light of 600 nm wavelength is

The number of de-Broglie wavelengths contained in the second Bohr orbit of hydrogen atom is