A light ray hits a mirror at a 30° angle to the normal. At what angle does it reflect?
A15°
B30°
C60°
D90°
The law of reflection states that the angle of reflection equals the angle of incidence. If the incoming angle is 30° to the normal, the reflected angle is also 30°.
Question 2 True / False
A pencil placed in a glass of water appears bent at the surface because of refraction.
TTrue
FFalse
Answer: True
Light from the submerged part of the pencil changes direction (refracts) as it passes from water to air. Your brain traces the light back in a straight line, making the pencil appear bent.
Question 3 Short Answer
Why does light bend when it enters water from air?
Think about your answer, then reveal below.
Model answer: Light travels slower in water than in air. When the wave enters water at an angle, the part that enters first slows down while the rest continues at the original speed, causing the wave front to pivot and change direction.
Refraction is caused by a change in wave speed. The change in speed at the boundary between two media causes the wave to change direction, bending toward the slower medium.