Acoustics

Questions 1–10 of 55

Q1. What is the Doppler effect?

Change in observed frequency due to relative motion of source and observer Sound speed always becomes zero Sound is never reflected Only amplitude changes

Q2. What mainly distinguishes the quality or timbre of sounds?

Overtone composition and waveform Only fundamental frequency Only sound speed Only temperature

Q3. Why is sufficient distance from a reflecting surface needed to hear a distinct echo?

To make the time delay of reflected sound distinct To make sound speed zero To change sound colour To convert sound into heat

Q4. What is the SI unit of sound intensity?

W m⁻² W dB N

Q5. Can sound travel through vacuum?

No Yes Only in vacuum Only with light

Q6. Which measure can help reduce noise in cities?

Planting trees and using sound barriers Using more horns Locating industries inside residential areas Increasing loudspeakers

Q7. What is a likely effect of excessive reverberation?

Speech clarity decreases Speech becomes clearer Sound disappears completely Frequency becomes zero

Q8. What can be measured using an echo?

Distance Voltage Temperature Resistance

Q9. What is the wavelength of sound travelling at 330 m/s with frequency 660 Hz?

0.5 m 2 m 990 m 330 m

Q10. In a longitudinal wave, the low-pressure region is called:

Rarefaction Compression Crest Trough