When light reaches the boundary between two materials, some light may be reflected back into the first material while some is refracted into the second. Angles of incidence, reflection, and refraction are measured from the perpendicular, or normal, to the surface.
If light travels from a material with a higher refractive index n1 into one with a lower refractive index n2, where n1>n2, the refracted ray bends away from the normal. In this situation, the refracted angle θ2 is greater than the incident angle θ1. The reflected ray still obeys the law of reflection: its angle equals the angle of incidence.
All flashcards
What is the normal to a boundary?
An imaginary line perpendicular to the boundary, from which incidence, reflection, and refraction angles are measured.
What is the critical-angle formula?
For light traveling from higher to lower refractive index, θc=sin−1(n2/n1), where n1>n2.
How do the core and cladding guide light in an optical fiber?
The core has a higher refractive index than the cladding, enabling total internal reflection at their boundary.
How can an endoscope use optical fibers?
One fiber bundle can carry light inward, while another carries reflected light back for viewing or imaging.
What causes colors in light emerging from a clear diamond?
Dispersion: different wavelengths of light are refracted by different amounts.
Quiz questions
Which conditions must be met for total internal reflection at a boundary?Answer: Light travels from higher to lower refractive index, and the incidence angle exceeds the critical angle.
When light passes from a higher-index material into a lower-index material below the critical angle, how does the refracted ray bend?Answer: Away from the normal, making the refracted angle larger than the incident angle.
Why can total internal reflection guide light along an optical fiber?Answer: Light reflects repeatedly at the core boundary when the core has higher refractive index and the incidence angle exceeds critical.
How can a reflecting arrangement based on total internal reflection redirect light in a periscope?Answer: Its reflective surfaces redirect the light path through internal reflections.
Why is the critical angle for a diamond–air boundary small?Answer: Diamond has a high refractive index relative to air.
Based on University Physics Volume 3 by Samuel J. Ling, Jeff Sanny, William Moebs (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.