Question

1.  When light waves strike a mirror, they change direction.

2.  Light waves travel at the same speed in all materials.

ANSWER THE FOLLOWING QUESTIONS (READ PAGES 456-461)

1.Visual Check (458)  Do tires usually absorb, transmit, or reflect light waves?  Explain your answer.

2.  Reading Check (458)  Give one reason why the energy carried by sound waves decreases as those sound waves travel through air.

3.  Key Concept Check (458)  What are three ways that waves interact with matter?

4.  Reading Check (459)  What is the Law of Reflection?

5.  Key Concept Check (461)  Compare and contrast reflection, refraction, and diffraction.

Answer 1

Brief answers from pages 456–461:

1. Visual Check (458) — Do tires usually absorb, transmit, or reflect light waves? Explain.
- Tires mostly absorb light. They are opaque and dark (black), so most visible light is absorbed and converted to heat; only a small amount is reflected (mostly diffuse reflection from the rough surface). Tires do not transmit light.

2. Reading Check (458) — Give one reason why the energy carried by sound waves decreases as those sound waves travel through air.
- Energy decreases because it is absorbed by the air (viscous and thermal losses) and because the wave spreads out (geometric spreading), so intensity falls with distance.

3. Key Concept Check (458) — What are three ways that waves interact with matter?
- Absorption (energy taken up by the material), reflection (wave bounces off a surface), and transmission/refraction (wave passes into another material and may change direction and speed).

4. Reading Check (459) — What is the Law of Reflection?
- The angle of incidence equals the angle of reflection (both measured from the normal). The incident ray, reflected ray, and the normal all lie in the same plane.

5. Key Concept Check (461) — Compare and contrast reflection, refraction, and diffraction.
- Reflection: wave bounces off a surface; angle of incidence = angle of reflection; stays in same medium. Example: mirror.
- Refraction: wave passes into a different medium and changes speed and direction (frequency stays the same, wavelength and speed change). Example: a straw appearing bent in water.
- Diffraction: wave bends around obstacles or spreads out after passing through an opening; amount of bending depends on the wavelength relative to the obstacle/opening size. Example: sound heard around a corner.
- Contrast: reflection involves bouncing, refraction involves speed change at a boundary, diffraction involves bending around obstacles or through slits and does not require a change of medium.