RRB Junior Engineer / DMS / CMA 2019 · Question 150 of 3719

What is the speed of light in air?

Physics - Optics

Aa. 3 × 10⁶ m/s
Bb. 3 × 10⁸ m/sCorrect
Cc. 3 × 10⁴ m/s
Dd. 3 × 10⁵ m/s

Answer: B. b. 3 × 10⁸ m/s

Explanation

Light travels in a straight line. Light in the air is 1.0003 times slower than light in a vacuum, which slows it all the way down from 299,792,458 meters per second to 299,702,547 meters per second. That's a slowdown of 89,911 meters per second, which looks like a lot but is only three ten- thousandths of the speed of light. The speed of light in the air is 3 x 108 m/s.

Source: RRB JE 2019 CBT-1 (24-May-2019 Shift-1) — ixambee compilation with answer key and solutions · reliable-secondary

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