(a)  Briefly explain the following terms:
(i)  emission line spectra;
(ii)   line absorption spectra.

(b) Draw a labeled diagram showing the structure of a simple type of photocell and explain its mode of operation.

(c) State two
      (i)  reasons to show that x-rays are waves;
       (ii)  uses of x-rays other than in medicine.

(d) An electron jumps from an energy level of -1.6eV to one of -1.4 eV in an atom.  Calculate the energy and wavelength of the emitted radiation. [ h = 6.6 x 10\(^{-34}\) Js; c = 3.00 x 10\(^8\) ms\(^{-1}\); eV = 1.6 x 10\(^{-19}\) J ]