A beam of light in glass (n=1.5) strikes the glass-air interface at an angle of 60°. What happens to the light?
Practice Questions
1 question
Q1
A beam of light in glass (n=1.5) strikes the glass-air interface at an angle of 60°. What happens to the light?
It is refracted into the air.
It undergoes total internal reflection.
It is absorbed by the glass.
It is scattered.
Since the angle of incidence (60°) is greater than the critical angle (approximately 41.8° for glass to air), total internal reflection occurs.
Questions & Step-by-step Solutions
1 item
Q
Q: A beam of light in glass (n=1.5) strikes the glass-air interface at an angle of 60°. What happens to the light?
Solution: Since the angle of incidence (60°) is greater than the critical angle (approximately 41.8° for glass to air), total internal reflection occurs.
Steps: 5
Step 1: Identify the medium the light is traveling through. In this case, the light is in glass, which has a refractive index (n) of 1.5.
Step 2: Determine the angle at which the light strikes the glass-air interface. The angle of incidence is given as 60°.
Step 3: Calculate the critical angle for the glass-air interface. The critical angle can be found using the formula: critical angle = arcsin(1/n), where n is the refractive index of the glass. For glass (n=1.5), the critical angle is approximately 41.8°.
Step 4: Compare the angle of incidence (60°) with the critical angle (41.8°). Since 60° is greater than 41.8°, this means the light cannot pass into the air.
Step 5: Conclude that total internal reflection occurs because the angle of incidence is greater than the critical angle.
