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Light goes from flint glass into ethanol. The angle of refraction in the ethanol is 26.1°, the index of refraction for flint glass is 1.61, and the index of refraction for ethanol is 1.36. What is the angle of incidence in the glass? Answer in units of...

a) degrees
b) radians
c) arcseconds
d) gradians

1 Answer

1 vote

Final answer:

To find, the angle of incidence in the glass, we can use Snell's law. The angle of incidence in the glass can be calculated using the formula: sin(angle of incidence in glass) / sin(angle of refraction in ethanol) = index of refraction of ethanol / index of refraction of flint glass.

So, the correct answer is:

a) \( \theta_1 \approx 21.49^\circ \)

b) \( \theta_1 \approx 21.49^\circ \)

c) \( \theta_1 \approx 21.49^\circ \)

d) \( \theta_1 \approx 21.49^\circ \)

Step-by-step explanation:

To solve this problem, we can use Snell's Law, which relates the angles of incidence and refraction to the indices of refraction of the two media. Snell's Law is given by:

\[ n_1 \sin(\theta_1) = n_2 \sin(\theta_2) \]

where:

- \( n_1 \) is the index of refraction of the first medium (flint glass),

- \( \theta_1 \) is the angle of incidence in the first medium,

- \( n_2 \) is the index of refraction of the second medium (ethanol),

- \( \theta_2 \) is the angle of refraction in the second medium.

In this case:

- \( n_1 = 1.61 \) (index of refraction for flint glass),

- \( \theta_2 = 26.1^\circ \) (angle of refraction in ethanol),

- \( n_2 = 1.36 \) (index of refraction for ethanol).

We want to find \( \theta_1 \), the angle of incidence in the flint glass.

First, let's rearrange Snell's Law to solve for \( \theta_1 \):

\[ \theta_1 = \sin^{-1}\left(\frac{n_2}{n_1} \sin(\theta_2)\right) \]

Now, plug in the values:

\[ \theta_1 = \sin^{-1}\left(\frac{1.36}{1.61} \sin(26.1^\circ)\right) \]

Now, calculate \( \theta_1 \). Make sure your calculator is set to degrees mode.

Certainly, let's continue with the calculation:

\[ \theta_1 = \sin^{-1}\left(\frac{1.36}{1.61} \sin(26.1^\circ)\right) \]

Now, substitute the values and compute the expression:

\[ \theta_1 = \sin^{-1}\left(\frac{1.36}{1.61} \times \sin(26.1^\circ)\right) \]

\[ \theta_1 \approx \sin^{-1}\left(\frac{1.36}{1.61} \times 0.43837\right) \]

\[ \theta_1 \approx \sin^{-1}(0.37052) \]

Use the arcsine function on your calculator to find the angle:

\[ \theta_1 \approx 21.49^\circ \]

Now that we have the angle of incidence (\( \theta_1 \)), you can select the appropriate answer format. In this case, it is given in degrees. So, the correct answer is:

a) \( \theta_1 \approx 21.49^\circ \)

User Even Cheng
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