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MCQ practice · SSC Physics Board questions · Chapter 8: Reflection of Light

Dhaka Board 2021

The image formed in the mirror will be-

  1. i. real
  2. ii. inverted
  3. iii. 30 cm away

Think it through first, then pick an option.

  1. a i and ii
  2. b i and iii
  3. c ii and iii
  4. d i, ii and iii
Answer and explanation

Correct answer: d i, ii and iii

The diameter is 40 cm, so r = 20 cm and f = 10 cm. The object u = 15 cm is outside the focus. 1/v = 1/10 − 1/15 = 1/30, v = 30 cm. Outside the focus the image is real (i) and inverted (ii); the distance is 30 cm (iii).

Why the other options are wrong

  • a i and ii: This is not the answer: i and ii are true, but iii is true as well: v = 30 cm. So all three are correct.
  • b i and iii: This is not the answer: i and iii are true, but ii is true as well: the real image of an object outside the focus is inverted. So all three are correct.
  • c ii and iii: This is not the answer: ii and iii are true, but i is true as well: the object is outside the focus, so the image is real. So all three are correct.

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