Question

4. What is the angle of refraction in water for a ray of light that has an angle of incidence of 45 degrees as it enters a layer of oil from the air above? ( nair=1, noit=1.15, nwater=1.33) a) 27 degrees b) 32 degrees c) 36 degrees d) 39 degrees 5. A radar receiver indicates that a transmitted light pulse return as an echo in 20us after transmission. How far away is the reflecting object? a) 1.5 Km b) 3.0 Km c) 6.0 Km d) 9.0 Km 6. In a vacuum, the velocity of all electromagnetic waves a) is zero b) is nearly 3x10 m/s c) depends on the frequency d) depends on the amplitude

Answer 1

4.

At air oil interference

By snell's law

Sini/Sinr = n2/n1

Sin45/Sinr1= 1.15/1

r1 = 38o​​​​​​

Now snell's law at the oil water interface

Sinr1/Sinr2 = nwater /noil

Sin38/Sinr2 = 1.33/1.15

r2 = 32.16o​​​​​​

So angle of refraction in water surface = 32.16o

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