Multiple choice

Which of the following is called focus or focal point?

  1. The centre of a spherical mirror

  2. The centre of a hollow sphere of glass of which the spherical mirror is a part

  3. The portion of a mirror from which the reflection of light actually takes place

  4. The point on the principal axis where all the rays coming from infinity (parallel rays) after reflection either meet or appear to meet
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The focus (or focal point) is the point on the principal axis where light rays parallel to the axis converge or appear to diverge from after reflection.

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