A point source of light is moving at a rate of `2 cm-s^(-1)` towards a thin convex lens of focal length 10 cm along its optical axis. When the source is 15 cm away from the lens the image is moving at -

A convex lens of focal length 15 cm is placed on a plane mirror. An object is placed at 30 cm from the lens. The image is

A convex lens of focal length 15 cm is placed on a plane mirror. An object is placed at 30 cm from the lens. The image is

A point source S is placed at a distance of 15 cm from a converging lens of focal length 10 cm on its principal axis. Where should a diverging miror of focal length 12 cm be placed to that a real image is formed on the source itself.

A point source S is placed at a distance of 15 cm from a converging lens of focal length 10 cm on its principal axis. Where should a diverging miror of focal length 12 cm be placed to that a real image is formed on the source itself.

A point source S is placed at a distance of 15 cm from a converging lens of focal length 10 cm on its principal axis. Where should a diverging miror of focal length 12 cm be placed to that a real image is formed on the source itself.

A point object is placed at a distance of 20cm from a thin plano-convex lens of focal length 15cm If the plane surface is silvered.the image will form at

A thin convex lens of focal length 10 cm and a thin concave lens of focal length 26.2 cm are in contact. The combination acts as

A thin convex lens of focal length 10 cm and a thin concave lens of focal length 20 cm are in contact. The combination acts as :