When waves are reflected, absorbed or passed through
Grade 8 Science Worksheet - Building Confidence
Circle the best answer, or write your answer on the line.
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Light on three materials (example data)
material reflected (%) absorbed (%) Clear glass 8 2 Tinted glass 6 54 Mirror 95 4 Light that is not reflected or absorbed is transmitted.
Ari tests three materials with a flashlight. What percent of the light does the tinted glass transmit?
Bo shines a lamp on three materials. What percent of the light does the window film transmit?
A lamp shines on three materials. What percent of the light does the lampshade transmit, Esme?
Sunglass lenses tested with a lamp (example data)
lens reflected (%) absorbed (%) transmitted (%) A 5 15 80 B 6 74 20 C 60 10 30 Kira wants sunglasses that let the least light reach the eyes. Which lens should be chosen?
- Lens A, since it lets 80% of the light through, the largest share of the three lenses
- Lens B, since just 20% of the light passes through it to the eyes
- Lens A, since it absorbs the least light, so it keeps the light from heating the eyes
- Lens C, since it reflects the most light, 60%, and reflected light does not reach the eyes
Mirror test (example data)
angle of incidence from the normal (°) angle of reflection from the normal (°) 20 20 35 35 50 50 A ray hits a mirror at 60° from the normal. What is the angle of reflection from the normal, Milo?
- 60° from the normal, equal to the angle of incidence
- 55°, since the mirror absorbs a little light in the bounce
- 30°, the angle between the reflected ray and the mirror surface
- 120°, the angle between the incoming ray and the reflected ray
A ray leaves a mirror at 25° from the normal. What was its angle of incidence from the normal, Noah?
- 20°, since the light lost some energy on the way into the mirror
- 65°, the angle between the incoming ray and the mirror surface
- 25° from the normal, equal to the angle of reflection
- 50°, the angle between the incoming ray and the reflected ray
A ray strikes a mirror at 30° to the mirror's surface. What is its angle of reflection from the normal, Pia?
- 30°, the angle the question gives, which is already the angle of reflection
- 120°, the angle between the incoming ray and the reflected ray
- 60° from the normal, since the ray is 90° − 30° from it
- 90°, since the ray turns a right angle at a flat mirror
Cloth in sunlight for 10 minutes (example data)
cloth temperature rise (°C) Black 14 White 5 A black cloth warmed more than a white cloth in the sun. Which explanation fits the data, Ren?
- The black cloth transmitted more light, which warmed the air trapped under it
- The white cloth absorbed the light, and the absorbed energy vanished, so it stayed cool
- The black cloth reflected the most light, and reflected light is what heats a cloth
- The black cloth absorbed more light, and absorbed light energy becomes thermal energy
Foam on a studio wall absorbs sound. What happens to the sound energy it absorbs, Tala?
- It becomes a very small amount of thermal energy in the foam
- It disappears, since energy is used up when a wave is absorbed
- It bounces back out of the foam as a quieter echo, and that counts as absorbing it
- It is stored in the foam as sound and released the next day as an echo
Echo length in a gym (example data)
room echo lasts (s) Bare gym 2 Gym with mats on the walls 0.6 Mats on the walls shortened a gym's echo. Which explanation fits the data, Zee?
- The mats reflected the sound up toward the ceiling, and reflecting quiets a room as absorbing does
- The mats absorbed some of the sound, so less was reflected back and the echo faded sooner
- The mats made the gym smaller, and a smaller room has a shorter echo whatever is on its walls
- The mats made the air in the gym colder, so the sound traveled slower and faded away