Reflection and Refraction Quiz
Questions: 16 · 10 minutes
1. A ray meets a reflective surface at 30° to the surface itself. What is its angle of incidence?
30°
120°
90°
60°
2. Why can a corner reflector send light back roughly toward its source over a range of incoming directions?
Successive reflections from mutually perpendicular surfaces reverse the ray's direction components.
It absorbs the incoming light and emits new light toward the source.
Its curved surface focuses all rays at one point.
It refracts every incoming ray until the ray follows the normal.
3. A narrow beam of white light passes through a glass prism. Which visible color is generally deviated most?
Red, because it has the longest visible wavelength
Green, because it lies near the middle of the visible spectrum
All colors, because glass has exactly the same refractive index for every wavelength
Violet, because glass generally has a higher refractive index for shorter visible wavelengths
4. When viewed from above, the bottom of a clear swimming pool often appears shallower than it really is. Why?
Rays from the bottom refract away from the normal as they leave the water, and the eye traces them backward to a shallower apparent position.
Rays from the bottom refract toward the normal as they leave the water, making the physical bottom rise.
The water reflects the bottom onto its surface like a plane mirror.
Light slows down after leaving the water, shortening the apparent distance.
5. Light travels from glass into air. How does its speed change after crossing the boundary?
It decreases because air has a greater refractive index than glass.
It increases because air has a lower refractive index than glass.
It becomes zero momentarily at the boundary.
It remains unchanged because only direction can change.
6. Which situation can produce total internal reflection?
Light strikes a plane mirror at an angle smaller than 45°.
Light travels from a lower-index medium to a higher-index medium at any incidence angle.
Light travels from a higher-index medium to a lower-index medium at an incidence angle greater than the critical angle.
Light crosses between two media at normal incidence.
7. A pencil partly submerged in water appears bent at the water's surface. What best explains this appearance?
Water physically bends the submerged part of the pencil.
Light from the pencil undergoes total internal reflection at every angle.
Light from the submerged section refracts as it passes from water into air.
The water surface acts only as a plane mirror.
8. When light crosses from air into glass, which property remains unchanged at the boundary?
Speed
Wavelength
Direction in every case
Frequency
9. Which statement correctly describes the law of reflection?
The angle of incidence equals the angle of reflection, with both measured from the mirror surface.
The angle of incidence equals the angle of reflection, with both measured from the normal.
The reflected ray always travels at 90° to the incident ray.
The reflected ray always follows the normal to the surface.
10. A plane mirror rotates by 10° while the incoming ray remains fixed. By how much does the reflected ray's direction rotate?
5°
20°
10°
40°
11. A ray passes from air into glass at an angle to the normal. In which direction does it usually bend?
Along the boundary
Away from the normal
Toward the normal
Back along the incident path
12. A light ray strikes a flat mirror directly along the normal. What happens to it?
It reflects at 90° to its original path.
It bends toward the normal inside the mirror.
It travels along the surface of the mirror.
It returns along the same path in the opposite direction.
13. A light ray passes through a glass slab whose two faces are parallel. How does the emerging ray compare with the original incident ray?
It always emerges along the normal.
It emerges parallel to the incident ray but may be laterally displaced.
It emerges perpendicular to the incident ray.
It returns toward the light source.
14. Why does a light ray usually change direction when it passes obliquely from air into glass?
Its speed changes as it enters a medium with a different refractive index.
The glass reflects every part of the ray.
Gravity pulls the ray toward the glass.
Its frequency changes at the boundary.
15. Which set of properties describes the image formed by an ordinary plane mirror?
Virtual, upright, and the same size as the object
Virtual, inverted, and larger than the object
Real, inverted, and smaller than the object
Real, upright, and the same size as the object
16. For a transparent material, how is its refractive index calculated using the speed of light in a vacuum and its speed in the material?
Divide the material speed by the square of the vacuum speed.
Add the vacuum speed to the material speed.
Divide the vacuum speed by the material speed.
Divide the material speed by the vacuum speed.