25 As light travels from air to a medium such as glass which

25. As light travels from air to a medium such as glass which of the following properties remains the same? (B) wave speed (A) frequency (C) wavelength D) All 3 remain the same 26. A layer of ice n 1.31 having parallel slides floats on water n- 1.33. If light is incident on the upper surface of the ice at an angle of incidence of 40°.what is the angle of refraction in the water? (C) 29.4° (B) 28.9 (A) 0.48° 27. A beam of light is both reflected and refracted at the surface between air and glass. If the index of refraction of e, I glass is n 1.52, what is the angle of incidence 01 such that the reflected and refracted rays are perpendicular? The identity sin(90° coso may be helpful. (A) 41.1 (B) 45.0 (D) 56.7 (C) 48.9°

Solution

According to the given problem,

25.) A : frequency

26.) Given, n_air = 1, n_ice=1.31, n_water =1.33

Using snells law from air to ice:
n_airsin₁ = n_ice sin₂
1*sin40° =1.31 sin_2
2 = sin^-10.4906 = 29.38°

Using snells law again ice to water:

1.31sin29.38° = 1.33sin<sub>3

3</sub> = sin^-1 = 28.90° [B]

27.) By Snell\'s law,

Sin ₁/Sin₂ = n_g/n_a
Sin ₁/Sin (90 - ₁) = n_g/1
Sin ₁/Cos ₁ = n_g
tan ₁ = n_g

₁ = tan^-11.52 = 56.66° [D]