The refractive index of a medium is 1.5. The speed of light in this medium is:
A. 2×10⁸ m/s
B. 4.5×10⁸ m/s
C. 3×10⁸ m/s
D. 1.5×10⁸ m/s
Answer: Option A
Solution (By JKSSB Mock Tests)
Refractive index n = c/v, where c = 3×10⁸ m/s (vacuum speed). Thus v = c/n = 3×10⁸ / 1.5 = 2×10⁸ m/s. This direct calculation tests optics fundamentals. Memory aid: 'Higher n ⇒ slower light; v = c/n'. Competitive exams frequently test this with common refractive indices. Always use c = 3×10⁸ m/s unless specified; verify units (m/s). This problem assesses basic formula application skills essential for wave optics sections.
Explanation:
In a longitudinal wave, the particles of the medium vibrate back and forth parallel to the direction of wave propagation (creating compressions and rarefactions). Sound waves traveling through air are mechanical longitudinal waves. Light and radio waves are transverse electromagnetic waves, while surface water waves are a combination of both.
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