The electron in the hydrogen atom jumps from excited state (n = 3) to its ground state (n = 1) and the photons thus emitted irradiate a photosensitive material. If the work function of the material is 5.1 eV, the stopping potential is estimated to be (the energy of the electron in n^th state E_n = $${{ - 13.6} \over {{n^2}}}eV$$)

A source S₁ is producing, 10¹⁵ photons per second of wavelength 5000 $$\mathop A\limits^ \circ $$. Another source S₂ is producing 1.02 $$ \times $$ 10¹⁵ photons per second of wavelength 5100 $$\mathop A\limits^ \circ $$. Then, (power of S₂)/(power of S₁) is equal to

The potential difference that must be applied to stop the fastest photoelectrons emitted by a nickel surface, having work functions 5.01 eV, when ultraviolet light of 200 nm falls on it, must be

A beam of cathode rays is subjected to crossed electric (E) and magnetic fields (B). The fields are adjusted such that the beam is not deflected. The specific charge of the cathode rays is given by

(Where V is the potential difference between cathode and anode)