BMST Waves, Sound, and Light 5 — Questions and Answers
Question 1: The speed of light in a vacuum is approximately:
- 3 × 10⁶ m/s
- 3 × 10⁸ m/s (Correct answer)
- 3 × 10¹⁰ m/s
- 3 × 10⁴ m/s
Correct answer: 3 × 10⁸ m/s
The speed of light in a vacuum is approximately 3 × 10⁸ meters per second (about 300,000 km/s).
Question 2: A sound source moves toward a stationary observer. The observer will hear a sound with:
- Lower frequency than emitted
- The same frequency as emitted
- Higher frequency than emitted (Correct answer)
- No detectable frequency change
Correct answer: Higher frequency than emitted
When a source moves toward an observer, the Doppler effect causes the observed frequency to be higher than the emitted frequency.
Question 3: Which color of visible light has the shortest wavelength?
- Red
- Green
- Yellow
- Violet (Correct answer)
Correct answer: Violet
Violet light has the shortest wavelength in the visible spectrum, around 380–450 nm.
Question 4: Longitudinal waves differ from transverse waves in that the medium particles move:
- Perpendicular to the direction of wave travel
- Parallel to the direction of wave travel (Correct answer)
- In circular paths
- In random directions
Correct answer: Parallel to the direction of wave travel
In longitudinal waves, particles of the medium vibrate parallel to the direction the wave travels, creating compressions and rarefactions.
Question 5: When two waves interfere destructively, the resulting amplitude is:
- The sum of both amplitudes
- Greater than either individual amplitude
- Reduced or zero (Correct answer)
- Unchanged
Correct answer: Reduced or zero
Destructive interference occurs when crests align with troughs, partially or fully canceling each other to reduce the amplitude.
Question 6: A material that allows light to pass through but scatters it so objects appear blurry is called:
- Opaque
- Translucent (Correct answer)
- Transparent
- Reflective
Correct answer: Translucent
Translucent materials transmit light but scatter it, making objects behind them appear blurry or indistinct.
Question 7: Which of the following best explains why the sky appears blue?
- Blue light is absorbed by the atmosphere more than other colors
- Blue light is reflected by the ocean below
- Blue light is scattered more by atmospheric particles due to its shorter wavelength (Correct answer)
- Blue light travels faster through air than other colors
Correct answer: Blue light is scattered more by atmospheric particles due to its shorter wavelength
Rayleigh scattering causes shorter-wavelength blue light to scatter more in all directions through the atmosphere, making the sky appear blue.
BMST Waves, Sound, and Light 5
The speed of light in a vacuum is approximately: