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The velocity of e.m. waves of wavelength 5000 A in a medium of refractive index 2 is ______ m/s.

Asked in GUJCET 2016 · Snell's law, slabs and apparent depth

Answer: (2) 1.5×10⁸

Step-by-step solution

Given: refractive index of the medium n = 2; wavelength 5000 A.

Idea: the refractive index is defined by n = c/v, so v = c/n.

v = (3×10⁸)/2 = 1.5×10⁸ m/s.

The wavelength is given only to say which light it is; the speed in the medium depends on n alone.

So the velocity is 1.5×10⁸ m/s.

Why the other options are wrong

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