If the refractive index of a medium is 2.0, what is the critical angle for total
Practice Questions
Q1
If the refractive index of a medium is 2.0, what is the critical angle for total internal reflection when light travels from this medium to air?
30°
45°
60°
90°
Questions & Step-by-Step Solutions
If the refractive index of a medium is 2.0, what is the critical angle for total internal reflection when light travels from this medium to air?
Correct Answer: 60°
Step 1: Identify the refractive index of the medium (n1) and air (n2). Here, n1 = 2.0 and n2 = 1.0.
Step 2: Use the formula for the critical angle: sin(θc) = n2/n1.
Step 3: Substitute the values into the formula: sin(θc) = 1.0/2.0.
Step 4: Calculate the value: sin(θc) = 0.5.
Step 5: Find the critical angle (θc) by using the inverse sine function: θc = sin⁻¹(0.5).
Step 6: Determine the angle: θc = 30°.
Refractive Index – The refractive index is a measure of how much light slows down in a medium compared to its speed in a vacuum.
Total Internal Reflection – Total internal reflection occurs when light attempts to move from a denser medium to a less dense medium at an angle greater than the critical angle.
Critical Angle – The critical angle is the angle of incidence above which total internal reflection occurs.
Snell's Law – Snell's Law relates the angles of incidence and refraction to the refractive indices of the two media.
