A ray parallel to principal axis is incident at \(30^{\circ}\) from normal on concave mirror having radius of curvature \(R\). The point on principal axis where rays are focussed is \(Q\) such that \(PQ\) is
A ray parallel to principal axis is incident at \(30^{\circ}\) from normal on concave mirror having radius of curvature \(R\). The point on principal axis where rays are focussed is \(Q\) such that \(PQ\) is
- $\frac {R}{2}$
- $\frac{R}{\sqrt{3}}$
- $\frac{2\sqrt{R}-R}{\sqrt{2}}$
- $R\left(1-\frac{1}{\sqrt{2}}\right)$
The Correct Option is D
Solution and Explanation
$\frac{Q C}{\sin 30^{\circ}}=\frac{R}{\sin 120^{\circ}}$
or $Q C=R \times \frac{\sin 30^{\circ}}{\sin 120^{\circ}}=\frac{R}{\sqrt{3}}$
Thus $P Q=P C-Q C=R-\frac{R}{\sqrt{3}}$
$=R\left(1-\frac{1}{\sqrt{3}}\right)$
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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:
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Concepts Used:
Spherical Mirrors
A spherical mirror is a mirror which has been cut out of a spherical surface.
There are two kinds of spherical mirrors:
- Convex Mirror
- Concave Mirror
Concave Mirror
Concave mirrors are also called converging mirrors, because in these types of mirrors, light rays converge at a point after impact and reflect back from the reflective surface of the mirror.
Convex Mirror
The convex mirror has a reflective surface that is curved outward. Regardless of the distance between the subject and the mirrors, these mirrors are "always" virtual, upright and reduced.