BS Physics Fundamentals 2 — Questions and Answers
Question 1: Which property of a sound wave determines the pitch perceived by a listener?
- Amplitude
- Wavelength
- Frequency (Correct answer)
- Wave speed
Correct answer: Frequency
Frequency determines pitch — a higher frequency produces a higher perceived pitch.
Question 2: The Doppler effect describes the change in observed wave frequency due to:
- Light bending as it enters a new medium
- Relative motion between the source and the observer (Correct answer)
- Destructive interference between two waves
- Sound reflecting off a hard surface
Correct answer: Relative motion between the source and the observer
The Doppler effect occurs when relative motion between the source and observer causes the observed frequency to differ from the emitted frequency.
Question 3: When light travels from air into glass, according to Snell's law it:
- Speeds up and bends away from the normal
- Slows down and bends toward the normal (Correct answer)
- Maintains its speed and direction unchanged
- Slows down and bends away from the normal
Correct answer: Slows down and bends toward the normal
Entering a denser medium like glass, light slows down and bends toward the normal because the index of refraction of glass is greater than that of air.
Question 4: Constructive interference between two waves occurs when:
- Crests align with troughs
- The waves have different frequencies
- Crests align with crests and troughs align with troughs (Correct answer)
- One wave has zero amplitude
Correct answer: Crests align with crests and troughs align with troughs
Constructive interference results from waves that are in phase — crest meets crest and trough meets trough — producing a combined wave of greater amplitude.
Question 5: The approximate speed of sound in air at room temperature is:
- 3 × 10⁸ m/s
- 340 m/s (Correct answer)
- 1,500 m/s
- 100 m/s
Correct answer: 340 m/s
Sound travels at approximately 340 m/s in air at 20°C, far slower than the speed of light.
Question 6: Which type of electromagnetic radiation carries the highest energy per photon?
- Radio waves
- Visible light
- X-rays
- Gamma rays (Correct answer)
Correct answer: Gamma rays
Gamma rays have the highest frequency in the electromagnetic spectrum; since E = hf, they carry the greatest energy per photon.
Question 7: Einstein's explanation of the photoelectric effect demonstrated that light:
- Always behaves purely as a wave
- Can be polarized
- Has particle-like properties carried in discrete photons (Correct answer)
- Travels at different speeds in a vacuum depending on color
Correct answer: Has particle-like properties carried in discrete photons
The photoelectric effect showed that light delivers energy in quantized packets (photons), revealing its particle-like nature and earning Einstein the Nobel Prize.
BS Physics Fundamentals 2
Which property of a sound wave determines the pitch perceived by a listener?