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 1. A ray of light passes from air into water at an angle of 30.0 degrees. Find the...

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bwang96 | Student, Grade 11 | (Level 1) Salutatorian

Posted April 30, 2013 at 7:23 PM via web

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 1. A ray of light passes from air into water at an angle of 30.0 degrees. Find the angle of refraction. (22.1 degrees)

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ishpiro | Teacher | (Level 2) Associate Educator

Posted May 1, 2013 at 1:25 AM (Answer #1)

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To find the angle of refraction, use Snell's Law.

Here, `theta_1` is the angle of incidence (angle the ray makes with the normal to the surface) and `theta_2` is the angle the refracted ray makes with the normal to the surface - angle of refraction.

`sintheta_1/sintheta_2 = n_2/n_1`

The values of `n_1` and `n_2` , indices of refraction, are `n_1 = 1` for air and `n_2 = 1.33` for water. Plugging in these values and also `sintheta_1 = sin30=1/2` , and using the property of proportion, solve for `sintheta_2` :

`sintheta_2 = (n_1sintheta_1)/n_2=(1/2)/1.33=0.38` 

From here, `theta_2 = 22.1` degrees.

 

 

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