Spherical Mirrors - Practice Questions & MCQ

 Spherical mirror-

It is a part of a transparent hollow sphere whose one surface is polished.

There are two types of spherical mirrors: concave, and convex.

In the above figure, A concave (left) and a convex (right) mirror is shown.

Some important terminology-

• Centre of curvature (C)- The Centre of the sphere of which the mirror is a part is called Centre of curvature.
• Pole (P)- The geometrical centre of the spherical reflecting surface.
• The radius of curvature (R)- The radius of the sphere of which the mirror is a part is called the radius of curvature.

or R=Distance between pole and centre of curvature

$
\left(\text { Note } \Rightarrow R_{\text {concave }}=-v e, \quad R_{\text {convex }}=+v e, R_{\text {plane }}=\infty\right)
$
 

• Principle axis- A line passing through P and C is known as the Principle axis.
• Focus (F)- When a narrow beam of rays of light, parallel to the principal axis and close to it, is incident on the surface of a mirror, the reflected beam is found to coverage to or appears to diverge from a point on the principal axis. This point is called the focus.

     or  An image point on the principal axis for which object is at  is called the focus.

        C, P, F for a concave mirror are shown in the below figure.

• Focal Length (f)- It is the distance between the pole and the principal focus. For spherical

  mirrors, $f=\frac{R}{2}$

  $
  \text { (i.e } \left.f_{\text {concare }}=-v e, f_{\text {convex }}=+v e, f_{\text {plane }}=\infty\right)
  $
   

• Focal plane- A plane passing from focus and perpendicular to the principal axis.