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Atoms — Physics STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 SciencePhysicsAtoms1 Mark
Question
For question two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.

  1. Both A and R are true, and R is the correct explanation of A.
  2. Both A and R are true, but R is NOT the correct explanation of A.
  3. A is true, but R is false.
  4. A is false and R is also false.

Assertion (A): Laser is used to measure distant object like moon.

Reason (R): They are highly coherent source of light.

✓

Answer

  1. Both A and R are true, and R is the correct explanation of A.

Explanation:

As laser is highly monochromatic and highly coherent, we can send as a laser beam to the moon, from where it comes back reflected without much loss of intensity. That's why the large distances can be measured accurately with the help of laser.

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