The speed of light in vacuum is
A{'text': '3.0 × 10⁸ m/s', 'label': 'A'}
B{'text': '3.0 × 10⁶ m/s', 'label': 'B'}
C{'text': '340 m/s', 'label': 'C'}
D{'text': '3.0 × 10¹⁰ m/s', 'label': 'D'}
Answer & Solution
Correct answer: A. {'text': '3.0 × 10⁸ m/s', 'label': 'A'}
1. NCERT gives c = 299,792,458 m/s ≈ 3 × 10⁸ m/s.
2. Light and all electromagnetic waves travel at c in vacuum.
3. 340 m/s is the approximate speed of sound in air (a mechanical wave).
4. c is a universal constant not requiring a medium.
_Source: NCERT Class 11 Physics, Ch 14 "Waves", §14.1_
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