PAGE 147

What is the definition of incidence?

• The modulation of light or sound waves as they bend around the edges of an obstacle.

• The change of direction of a ray of light as it passes obliquely from one medium into another.

• The return of light, sound, or radiant heat after striking a surface.

• The striking of a ray of light or sound wave on a surface.

What does the term 'opaque' mean?

• Impermeable to light.

• Transmitting and diffusing light so that bodies on the opposite side are not clearly visible.

• Capable of transmitting light so that bodies situated beyond or behind can be distinctly seen.

• Directed from a smooth, polished surface.

What is the law of reflection?

• The principle that when light or sound is reflected from a smooth surface, the angle of incidence is equal to the angle of reflection.

• The ratio of light or radiation reflected by a surface to that incident upon it.

• The ratio of the radiation absorbed by a surface to the total incident on the surface.

• The ratio of the radiation reflected by a surface to the total incident on the surface.

What is the angle of refraction?

• The angle that a refracted ray makes with a normal to the interface between two media at the point of incidence.

• The angle that a straight line, such as a ray of light falling on a surface, makes with a normal to the surface at the point of incidence.

• The angle that a reflected ray makes with a normal to a reflecting surface at the point of incidence.

• The angle that a ray of light makes with a normal to a surface.

What is the definition of transparent?

• Capable of transmitting light so that bodies situated beyond or behind can be distinctly seen.

• Transmitting and diffusing light so that bodies on the opposite side are not clearly visible.

• Impermeable to light.

• Directed from a smooth, polished surface.