A ray parallel to the principal axis is incident at 30° from normal on a concave mirror having a radius of curvature R. The point in principal axis where rays are focussed is Q such that PQ is
A ray parallel to the principal axis is incident at \(30^\circ\) from the normal on a concave mirror having radius of curvature \(R\). The point on the principal axis where rays are focused is \(O\) such that \(PQ\) is:
