A metal foot ruler is held at the edge of a table. It is pressed at its free end and then released. It vibrates.

(a) Name the vibrations produced.

(b) State one way to increase the frequency of these vibrations.

(a) Which electrical component protects the electric circuit in case of excess current and which can also be used as a switch?

(b) Name the wire to which this electrical component is connected in an electric circuit.

Calculate the power spent by a crane while lifting a load of mass 2000 kg, at velocity of 1.5 ms^-1. (g = 10 ms^-2).

(a) Is it possible for a concave lens to form an image of size two times that of the object? Write Yes or No.

(b) What will happen to the focal length of the lens if a part of the lens is covered with an opaque paper?