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Math Help - refraction of light

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    refraction of light

    a beam of light traveling in air is incident on a transparent plastic material at an angle of incidence of 50 degrees. The angle of refraction is 35 degrees. What is the index of refraction of the plastic?
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    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by twistedmexican View Post
    a beam of light traveling in air is incident on a transparent plastic material at an angle of incidence of 50 degrees. The angle of refraction is 35 degrees. What is the index of refraction of the plastic?
    we use Snell's law here:

    it states that:
    n_1 \sin \theta_1 = n_2 \sin \theta_2

    well, more generally, it states that \frac {\sin \theta_1}{\sin \theta_2} = \frac {v_1}{v_2} = \frac {n_2}{n_1}, but let's not worry about that

    where n_1 is the refractive index of the initial material (in this case, that of the air)
    n_2 is the refractive index of the final material (in this case, that of the plastic)
    \theta_1 is the angle of incidence
    \theta_2 is the angle of refraction

    you are expected to know that the refractive index of air, \theta_1 = 1.00029 \approx 1, just use 1, that's the regular convention

    the only unknown here is n_2 (which is what we are asked to find obviously), so plug everything else in the formula and solve for it, we have:

    n_2 = \frac {n_1 \sin \theta_1}{\sin \theta_2}

    i leave the rest to you
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