Q: How can the formation of images be visualised ?
Ans: Images can be visualised by drawing ray diagram. Some of the rays to be used to draw a ray diagram are listed:
(i) A ray parallel to the principal axis passes through the principal focus (or appears to diverge from the principal focus) after reflection.
(ii) A ray passing through the principal focus becomes parallel to the principal axis after reflection.
(iii) A ray passing through the centre of curvature of the mirror retraces its own path.
(iv) A ray incident at the pole is reflected with equal inclination to the principal axis.