Spherical Mirrors

 

Concave Mirror

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Concave mirror whose reflecting surface is towards the centre of the sphere of which the mirror is a part.

Convex Mirror

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Convex mirror is one whose reflecting surface is away from the centre of the sphere of which the mirror is a part.

Convex Mirror

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In the above diagram,

• 'C' is the centre of curvature of the spherical mirror, which is a part of the whole sphere.

• 'P' is called the vertex or pole of the mirror, which is the mid point or centre of the spherical mirror.

• 'CP' is called the radius of curvature (R) M₁M₂ is called the aperture of the mirror.

• The straight line joining the pole and the centre C extended on both sides is called the principal axis of the mirror.

Definitions

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Principal Focus

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F is a point on the principal axis of the mirror at which, rays incident on the mirror in a direction parallel to the axis actually meet or appear to diverge after reflection from the mirror. F is a real point in case of concave mirror and F is a virtual point in case of convex mirror.

Focal Length

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The distance of principal focus from the pole of the spherical mirror is called focal length (f) of the mirror.

i.e., PF = f

Radius of Curvature

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The distance of C from P is called radius of curvature of the mirror.

i.e., PC = R