An object is placed at the following distance from a convex lens of focal length 15cm:

1. 35cm
2. 30cm
3. 20cm
4. 10cm

Which position of the object will produce:

1. A magnified real image?
2. A magnified virtual image?
3. A diminished real image?
4. An image of same size as the object?

A communications satellite in orbit sends a parallel beam of signals down to earth. If these signals obey the same laws of reflection as light and are to be focussed onto a small receiving aerial, what should be the best shape of the metal 'dish' used to collect them?

Why does a beam of light when it enters glass at an angle? Why does it not bend if it inters the glass at right angles?

Draw ray diagrams showing the image formation by a convex lens when an object is placed:
At the focus of the lens.

List four properties of the image formed by a plane mirror.

Which kind of mirrors are used in the headlights of a motorcar and why?

The lens A produces a magnification of, -0.6 whereas lens B produces a magnification of +0.6:

1. What is the nature of lens A?
2. What is the nature of lens B?

What is observed when 2mL of dilute hydrochloric acid is added to 1g of sodium carbonate taken in a clean and dry test tube? Write chemical equation for the reaction involved.

The refractive indices of glass and water with respect to air are 3/2 and 4/3 respectively. If speed of light in glass is 2×108 m/s, find the speed of light in water.