(a) What is a polarizer?

(b) With the aid of a diagram, explain how a polarizer can be used to polarize a beam of unpolarized light.

Name one use of 'LASER' in each of the following areas:

(a) communication;

(b) medicine;

(c) security

The accelerating potential in a cathode ray oscilloscope is 2.5 kV. Calculate the maximum speed of the accelerated electrons. [ e = 1.6 x 10\(^{-19}\) C; Me = 9.1 x 10\(^{-31}\) kg]

Write down the name of:

(a) two particles used in explaining the wave nature of matter;

(b) one device whose invention is based on the wave nature of matter.

(a) what is Brownian motion?

(b) State the two inferences that can be drawn from Brownian motion experiment.