BMST Waves, Sound, and Light 4 — Questions and Answers
Question 1: A wave travels from water into air. Compared to its speed in water, the wave's speed in air will:
- Increase (Correct answer)
- Decrease
- Remain the same
- Drop to zero
Correct answer: Increase
Sound travels faster in denser media like water than in less dense media like air, so moving from water to air decreases speed; however, light travels faster in air than in water.
Question 2: Which property of a wave determines the pitch of a sound?
- Amplitude
- Frequency (Correct answer)
- Wavelength ratio
- Wave speed
Correct answer: Frequency
Frequency determines pitch; higher frequency vibrations produce higher-pitched sounds.
Question 3: When light passes through a prism, the colors separate because different wavelengths of light travel at different speeds inside the glass. This phenomenon is called:
- Reflection
- Diffraction
- Dispersion (Correct answer)
- Polarization
Correct answer: Dispersion
Dispersion is the separation of white light into its component colors due to different wavelengths refracting at different angles.
Question 4: Two waves are said to be 'in phase' when they:
- Have different frequencies
- Have equal amplitudes only
- Reach their crests and troughs at the same time (Correct answer)
- Travel in opposite directions
Correct answer: Reach their crests and troughs at the same time
Waves in phase have their crests and troughs aligned simultaneously, leading to constructive interference.
Question 5: A guitar string vibrating at its fundamental frequency also produces overtones. These overtones are called:
- Nodes
- Harmonics (Correct answer)
- Antinodes
- Troughs
Correct answer: Harmonics
Harmonics (overtones) are integer multiples of the fundamental frequency produced by a vibrating string.
Question 6: Which type of wave requires a medium (like air or water) to travel?
- Electromagnetic wave
- Radio wave
- Mechanical wave (Correct answer)
- Light wave
Correct answer: Mechanical wave
Mechanical waves require a physical medium to propagate, unlike electromagnetic waves that can travel through a vacuum.
Question 7: The bending of waves around obstacles or through openings is called:
- Refraction
- Reflection
- Diffraction (Correct answer)
- Absorption
Correct answer: Diffraction
Diffraction is the bending of waves around edges or through openings, and it is most noticeable when the opening is close in size to the wavelength.
BMST Waves, Sound, and Light 4
A wave travels from water into air.
Compared to its speed in water, the wave's speed in air will: