If a light ray in a medium with n=1.5 strikes a boundary with n=1.0 at an angle

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Question: If a light ray in a medium with n=1.5 strikes a boundary with n=1.0 at an angle of 70°, what will happen?

Options:

Correct Answer: Total internal reflection occurs

Solution:

Since the angle of incidence (70°) is greater than the critical angle (approximately 41.8°), total internal reflection occurs.

If a light ray in a medium with n=1.5 strikes a boundary with n=1.0 at an angle of 70°, what will happen?

If a light ray in a medium with n=1.5 strikes a boundary with n=1.0 at an angle of 70°, what will happen?

Correct Answer: Total internal reflection occurs.

Step 1: Identify the refractive indices of the two media. The first medium has n=1.5 and the second medium has n=1.0.
Step 2: Determine the angle of incidence, which is given as 70°.
Step 3: Calculate the critical angle using the formula: critical angle = arcsin(n2/n1), where n1 is the refractive index of the first medium (1.5) and n2 is the refractive index of the second medium (1.0).
Step 4: Calculate the critical angle: critical angle = arcsin(1.0/1.5) ≈ 41.8°.
Step 5: Compare the angle of incidence (70°) with the critical angle (41.8°). Since 70° is greater than 41.8°, total internal reflection will occur.
Step 6: Conclude that when the light ray strikes the boundary, it will reflect back into the first medium instead of passing into the second medium.

Refraction and Total Internal Reflection – Understanding how light behaves at the boundary between two media with different refractive indices, including the concept of critical angle.