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Concepts Of Physics MCQ Edition [Volume 1]PhysicsLight Waves

The speed of light emitted by a source is measured as v_A , v_B , and v_C by three observers A , B , and C , respectively. Observer A travels towards the source and observer C travels away from the source at an identical speed. Meanwhile, observer B remains stationary. The entire surrounding space is a vacuum.

Options

  1. Av_A < v_B < v_C
  2. Bv_B = 1 2 (v_A + v_C)
  3. Cv_A > v_B > v_C
  4. Dv_A = v_B = v_C

Correct answer

D. v_A = v_B = v_C

Step-by-step solution

According to the second postulate of the special theory of relativity, the speed of light in a vacuum is an absolute constant. It is completely independent of the relative motion between the source of light and the observer. Therefore, all three observers A , B , and C will measure the exact same speed of light, regardless of whether they are moving towards the source, moving away from it, or remaining stationary. Thus, we have v_A = v_B = v_C .

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