Suppose a beam of light has a single wavelength of 600 nm in air (index of refra

Question

Suppose a beam of light has a single wavelength of 600 nm in air (index of refraction is about 1). The beam travels into glass (index of 1.52). What happens to the wavelength? The wavelength is unaffected The wavelength is longer inside the glass than in air The wavelength is shorter inside the glass than in air A beam of light of single wavelength (600 nm) is perpendicular to a thin film of gasoline spilled on another thin film of water. The thickness of the film of equal to 200 nm. One part of the beam reflects off the surface of the gasoline and another goes inside the gasoline and reflects off the surface of the water. You then view both beams from above. How much extra distance did the 2^nd beam travel compared to the 1^st beam? The 2^nd beam does not travel any extra distance to get to you The 2^nd beam travels less than 200nm to get to you The 2^nd beam travels exactly 200 nm to get to you The 2^nd beam travels more than 200 nm to get to you

Explanation / Answer

5). When light travels from air to glass, then the refractive index of the glass is given as,

         n = speed of light in air/ speed of light in glass

Or,    n = wavelength of light in air/ wavelength of light in glass

Or,        1.52 = 600/ wavelength of light in glass

So, wavelength of light in glass = 600/1.52

                                                    = 394.736 nm

Therefore , wavelength of light decreases as it goes from air to glass.

6). The light travels double the thickness of the oil film.

Distance travelled by light = 2×200nm = 400 nm

Therefore, second beam travels more than 200 nm to reach us.

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