Name the lens which always forms a virtual image of an object.

Explain with the help of a diagram, why the convex lens is also called a converging lens.

Why does a ray of light passing through the centre of curvature of a concave mirror gets reflected along same path after reflection?

Show by drawing a ray-diagram that the image of an object formed by a concave lens is virtual, erect and diminished.

Draw a labelled ray diagram to show the formation of image of an object by a convex mirror. Mark clearly the pole, focus and centre of curvature on the diagram.

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?

A student focuses the image of a well illuminated distant object on a screen using a convex lens. After that he gradually moves the object towards the lens and each time focuses its image on the screen by adjusting the lens.

1. In which direction-towards the screen or away from the screen, does he move the lens?
2. What happens to the size of the image-does it decrease or increase?
3. What happens to the image on the screen when he moves the object very close to the lens?

1. Find the nature, position and magnification of the images formed by a convex lens of focal length 0.20 m if the object is placed at a distance of:

1. 0.50m
2. 0.25m
3. 0.15m

2. Which of the above cases represents the use of convex lens in a film projector, in a camera, and as a magnifying glass?

How is the reflection of light ray from a plane mirror different from the refraction of light ray as it enters a block of glass?