Two brass sphere of radii 5 cm and 10 cm are brought in contact with each other. Find the centre of gravity of the combination.

Two thin converging lenses of focal length 15 cm and 30 cm are held in contact with each other. The focal length of the combination is

If a concave lens of focal length 12 cm and a convex lens of focal length 20 cm are kept in contact with each other . (i) Find be the focal length of the combination ? (ii) What will be the behaviour of the combination ?

Fill in the blanks : If two lenses with focal lengths 10cm and 20 cm respectively are kept in contact with each other , the effective power of the combination is ………….

If a convex lens of focal length 20 cm and a concave lens of focal length 30 cm are kept in contact with each other . (i) What will be the focal length of the combination ? (ii) What will be the power of the combination ? (iii) What will be the behaviour of the combination ?

If two convex lenses of focal lengths 10 cm and 5 cm are kept in contact with each other , What is their combined focal length ?

Why two or more mercury drops form a single drop when brought in contact with each other?

Why two or more mercury drops form a single drop when brought in contact with each other ?