A ray of light is incident on an air-glass boundary at an angle \(\theta\). If the angle between the partially reflected ray and the refracted ray is 90°, calculate \(\theta\), given that the refractive index of glass is 1.50.

 In the diagram illustrated, a body of mass m slides on an inclined plane. Show that the coefficient M\(_g\) of friction between the surfaces in contact is tan \(\theta\).

(a) Explain the term electrodes in electric cells.

b) An electric current passing through an electrolyte for 2 minutes deposited 200 g of a substance. If the electrochemical equivalent of the substance is 8.33 x 10\(^{-4}\)g C\(^{-1}\), calculate the current passed.

Explain why sound waves cannot be plane Polarized.

a) Define surface tension.

(b) State two methods by which the surface tension of a liquid can be reduced.