(a) Describe an experiment to show how the frequency of the note emitted by a vibrating string depends on the tension in the string

(b) Draw diagrams showing a vibrating string fixed at both ends emitting (i) fundamental frequency (ii) second overtone indicate the nodes and antinodes on the diagrams

(c) With the aid of a ray diagram show how a virtual image of an object is formed by a (i) concave mirror (ii) converging lens