The focus of a convex mirror is at a distance of 30 cm from its pole. Its centre of curvature will be at a distance of ________ from the focus. 

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RRB Group D 8 Sept 2022 Shift 2 Official Paper
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  1. 45 cm
  2. 60 cm
  3. 30 cm
  4. 15 cm

Answer (Detailed Solution Below)

Option 3 : 30 cm
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Detailed Solution

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The correct answer is '30 cm'.

Key Points

  • A ray of light is made incident on a convex mirror, parallel to its principal axis.
  • After reflection, it will pass through the principal focus for point Q(given in question).
  • qImage15050
  • The relation between the focal length (f) and radius of curvature (R) of a Concvex mirror is that the focal length is equal to half of the radius of curvature i.e. R=2f.

           R = 2 x 30 = 60cm

The center of curvature will be at a distance equal to the focus length from the focus. i.e CF = R - f = 60- 30 = 30 cm.

Therefore, 'option 3' is correct.

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