Question

List the new Cartesian sign convention for reflection of light by spherical mirror. Draw a diagram and apply these conventions for calculating the focal length and nature of spherical mirror which forms a 1/3 times imagnied virtual image of an object placed 18 cm in front of it.
OR
With the help of a ray diagram, state what is meant by refraction of light. State Snell’s law for refraction of light and also express it mathematically. The refractive index of air with respect to glass is 2/3 and the refractive index of water with respect to air is 4/3. If the speed of light in glass is 2 × 10⁸ m/s, find the speed of light in (a) air, (b) water.

Answer 1

1. u is always negative
2. v is always positive