Question

BEFORE YOU READ/ AGREE OR DISAGREE

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

BEFORE YOU READ / Agree or disagree

1. When light waves strike a mirror, they change direction.
- Agree. A mirror causes reflection, so the light is redirected (bounces) from the surface.

2. Light waves travel at the same speed in all materials.
- Disagree. Light travels fastest in vacuum and changes speed depending on the optical properties of the material (index of refraction); different materials slow light by different amounts.

Questions (based on pp. 456–461)

1. Visual Check (p.458) — Do tires usually absorb, transmit, or reflect light waves? Explain.
- Tires mostly absorb light. They are dark and opaque, so very little light is transmitted; some light is diffusely reflected, but most incident visible light is absorbed and converted to heat.

2. Reading Check (p.458) — Give one reason why the energy carried by sound waves decreases as those sound waves travel through air.
- Sound energy decreases because it is spread over a larger area (geometric spreading) and because air absorbs and converts some sound energy into heat (attenuation due to viscosity and molecular interactions).

3. Key Concept Check (p.458) — What are three ways that waves interact with matter?
- Reflection (wave bounces off a surface), refraction (wave changes direction and speed when entering a different medium), and absorption (wave energy is taken up by the material and usually converted to heat). (Transmission is closely related to refraction/absorption.)

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

5. Key Concept Check (p.461) — Compare and contrast reflection, refraction, and diffraction.
- Reflection: Wave bounces off a boundary; direction changes but the wave stays in the same medium (example: mirror). Angle of incidence equals angle of reflection.
- Refraction: Wave passes into a different medium and changes speed and direction (example: a straw appearing bent in water). Described by Snell’s law; involves transmission into the new medium.
- Diffraction: Wave bends around edges or spreads out after passing through an opening; most noticeable when obstacle/opening size is comparable to the wavelength (example: sound around a corner or light through a narrow slit producing a pattern).
- Similarities/differences: All are wave behaviors at boundaries or obstacles. Reflection and refraction are boundary interactions where incidence at a surface determines outcome; refraction involves changing medium and speed, reflection does not. Diffraction involves bending due to obstacles/openings and is related to wavelength size; it does not require a change of medium.