Question

6. A beam of light in air is incident at an angle of 30° to the surface of a rectangular block of clear plastic (n = 1.46 ). The light beam first passes through the block and re-emerges from the opposite side into the air at what angle to that surface? a. 42° b. 23° c. 30° d. 59° 7 According to the photon energy formula, tripling the frequency of the radiation from a monochromatic source will change the energy content of the individually radiated photons by what factor? a. 0.33 b. 1.0 c. 1.73 d. 3.0 A fiber optic cable (n = 1.50 ) is submerged in water (n = 1.33 ). What is the critical angle for light to stay inside the cable? a, 83.10 b. 62.5° C. 41.8° d. 27.6 Page 2 of 6

Answer 1

i = 60° mal (air) 30 Gol In = 1.46 JA mal (ais) ! Let, o= angle of emerges from opposite side into air Apply Snell's Law at o, 1x Sini = nSing - Sing Sin 60° - Ta 1.46 - Now, apply Shell's Lako at A n Sing = 1x Sino Sine = 1.46X0.593168 0 = 60° 0.593168

So, angle of emerges light with the Surface - (90-0) = 90° -60° -30° Answer: (C) 30° photon energy, E = h = hd E = hy where, v is frequency Now, tripling frequency energy, I'=hx) = 360 E'= 3€ So, energy will be three time of its initial value, 8 Given, refractive index of fiber optic Cable, s, a los (core) Now refractive index of water (cladding) M = 1.33

(en.= .48 So, Critical angle,
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