Online Test — Sound
20 Questions • 15 min • Chapter MCQ
15:00
Question 1 of 20
Sound is produced by an object that is
vibrating
hot
charged
still
Explanation: All sound originates from a vibrating source.
Question 2 of 20
Sound cannot travel through
iron
vacuum
water
air
Explanation: A vacuum has no particles, so no mechanical wave can pass.
Question 3 of 20
Sound is a wave of the type
transverse
electromagnetic
longitudinal
stationary
Explanation: Particles vibrate parallel to the direction of travel.
Question 4 of 20
A region of high pressure and density in a sound wave is a
rarefaction
compression
crest
trough
Explanation: Compression = particles crowded, high pressure/density.
Question 5 of 20
The SI unit of frequency is
metre
second
newton
hertz
Explanation: Frequency is measured in hertz ($\text{Hz}$).
Question 6 of 20
The relation between speed, frequency and wavelength is
$v=\frac{f}{\lambda}$
$v=f\lambda$
$v=\frac{\lambda}{f}$
$v=f+\lambda$
Explanation: $v=f\lambda$ is the wave equation.
Question 7 of 20
The time period $T$ and frequency $f$ are related by
$T=f$
$T=2f$
$T=\frac{1}{f}$
$T=f^2$
Explanation: Period is the reciprocal of frequency.
Question 8 of 20
The loudness of a sound depends on its
frequency
amplitude
speed
wavelength
Explanation: Greater amplitude means louder sound.
Question 9 of 20
The pitch of a sound depends on its
frequency
amplitude
quality
speed
Explanation: Higher frequency gives higher pitch.
Question 10 of 20
A $340\,\text{Hz}$ note travelling at $340\,\text{m/s}$ has wavelength
$0.5\,\text{m}$
$1\,\text{m}$
$2\,\text{m}$
$340\,\text{m}$
Explanation: $\lambda=v/f=340/340=1\,\text{m}$.
Question 11 of 20
The human audible range of frequency is about
$2$–$200\,\text{Hz}$
$200$–$2000\,\text{Hz}$
above $20{,}000\,\text{Hz}$
$20$–$20{,}000\,\text{Hz}$
Explanation: Healthy ears hear $20\,\text{Hz}$ to $20{,}000\,\text{Hz}$.
Question 12 of 20
Sound of frequency below $20\,\text{Hz}$ is called
infrasound
ultrasound
audible sound
supersound
Explanation: Below the audible range is infrasound.
Question 13 of 20
Sound travels fastest in
air
water
steel
vacuum
Explanation: Solids have closely packed particles, so sound is fastest in steel.
Question 14 of 20
To hear a distinct echo, the reflected sound must return after at least
$0.01\,\text{s}$
$0.5\,\text{s}$
$0.1\,\text{s}$
$1\,\text{s}$
Explanation: The ear retains sound for about $0.1\,\text{s}$.
Question 15 of 20
With $v\approx344\,\text{m/s}$, the minimum distance for an echo is about
$1.72\,\text{m}$
$17.2\,\text{m}$
$34.4\,\text{m}$
$172\,\text{m}$
Explanation: $d=\frac{344\times0.1}{2}=17.2\,\text{m}$.
Question 16 of 20
A SONAR echo returns in $2\,\text{s}$ with $v=1500\,\text{m/s}$. The depth is
$3000\,\text{m}$
$750\,\text{m}$
$1500\,\text{m}$
$375\,\text{m}$
Explanation: $2d=v\times t=3000$, so $d=1500\,\text{m}$.
Question 17 of 20
Repeated overlapping reflection of sound in a hall is called
echo
reverberation
refraction
diffraction
Explanation: Persistent reflections give reverberation.
Question 18 of 20
Bats navigate in the dark mainly using
infrasound
ultrasound
visible light
radio waves
Explanation: Bats use ultrasonic echolocation.
Question 19 of 20
In a sound wave, what is actually transported from source to listener?
air particles
energy
water
vacuum
Explanation: Particles only oscillate; energy is what travels.
Question 20 of 20
Two instruments playing the same note at the same loudness differ in
frequency
amplitude
quality (timbre)
speed
Explanation: Timbre distinguishes sources of identical pitch and loudness.