Which of the following statements is true for a concave mirror?

Focal length of concave mirror is always positive Focal length of concave mirror is always negative Focal length of concave mirror is zero Focal length of concave mirror is infinite

Focal length of concave mirror is always negative

A spherical mirror, whose reflecting surface is curved inwards, that is, faces towards the centre of the sphere, is called a concave mirror. Focal length of concave mirror is always negative.