MCQ practice · SSC Physics Board questions · Chapter 7: Waves and Sound
The unit of sound intensity−
Think it through first, then pick an option.
- a Wm
- b Wm⁻¹
- c Wm⁻²
- d W⁻¹m
Answer and explanation
Correct answer: c Wm⁻²
Right. Intensity = power ÷ area = W m⁻².
Why the other options are wrong
- a Wm: W m is power × length. Intensity divides by area; it does not multiply.
- b Wm⁻¹: W m⁻¹ is power ÷ length. The division is by area (m²), not by length (m).
- d W⁻¹m: W⁻¹ m puts power underneath, the wrong way up. Power goes on top and area underneath.
More board questions on this topic
- The unit of sound intensity is−
- The pitch of a musical sound:
- What kind of wave is sound?
- In which of the following media is the speed of sound the lowest?
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