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Q52
(NDA-II/2023)
Science & Technology › Basic Science (Physics, Chemistry, Biology)
Official Key
The flash of lightning is seen before the thunderstorm is heard. It verifies that
Result
Your answer:
—
·
Correct:
B
Explanation
The observation that lightning is seen before thunder is heard is a direct consequence of the significant difference between the speed of light and the speed of sound in the atmosphere.
- Speed of Light: Light travels at an incredible speed of approximately 300,000,000 meters per second (3 × 108 m/s) in air. This allows the visual flash to reach our eyes almost instantaneously after the discharge occurs.
- Speed of Sound: Sound travels much slower, at approximately 343 meters per second in air (at 20°C).
Because light travels nearly a million times faster than sound, the visual signal of the lightning strike covers the distance to the observer much quicker than the pressure waves (thunder) produced by the same event. Therefore, Option B is correct as it verifies that light travels much faster than sound.
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