Sound cannot travel through which of the following?
- A.Air
- B.Water
- C.Vacuum
- D.Iron
Correct answer
Explanation
The correct answer is C, vacuum. A vacuum contains no particles, and a mechanical wave such as sound can travel only by making particles vibrate and hand the disturbance on to their neighbours. The bell jar experiment shows this clearly: an electric bell ringing inside a glass jar grows fainter and finally inaudible as the air is pumped out, although the hammer can still be seen striking the gong.
Option A, air, carries sound at about 340 metres per second at room temperature and is the medium in which we normally hear. Option B, water, carries it faster, at roughly 1500 metres per second, which is why whales and SONAR can communicate and search over long distances at sea. Option D, iron, is a solid with tightly packed particles and carries sound fastest of the three, at several thousand metres per second.
Read the full article: Sound and Waves: Properties, Speed and PYQs
Practice Questions
View allThe frequency of a sound wave is 50 Hz and its wavelength is 4 m. What is the distance travelled by the sound wave in 3 s?
- A.100 m
- B.600 m
- C.200 m
- D.300 m
Show answer
The speed of a wave is the product of its frequency and its wavelength, so the speed here is 50 hertz multiplied by 4 metres, that is 200 metres per second.
Read the full explanation →The brain interprets the frequency of an emitted sound called -
- A.Wavelength
- B.Wave velocity
- C.Pitch
- D.Oscillation
Show answer
Pitch is the characteristic of a sound by which the brain judges it as shrill or flat, and it is decided by the frequency of the wave.
Read the full explanation →A sound wave has a frequency of 1 kHz and wavelength 50 cm. How long will it take to travel 1 km?
- A.5 s
- B.4 s
- C.3 s
- D.2 s
Show answer
Convert the units first: 1 kilohertz is 1000 hertz and 50 centimetres is 0.5 metre. The speed is frequency multiplied by wavelength, that is 1000 multiplied by 0.5, which gives 500 metres per second.
Read the full explanation →The loudness of sound depends upon the
- A.velocity of sound waves in the medium.
- B.amplitude of the sound waves.
- C.frequency of the sound waves.
- D.frequency and velocity of the sound waves.
Show answer
Amplitude is the maximum displacement of a particle of the medium from its rest position, and the energy carried by a wave increases with the square of the amplitude.
Read the full explanation →The flash of lightning is seen before the thunderstorm is heard. It verifies that
- A.sound travels much faster than light
- B.light travels much faster than sound
- C.light and sound both travel with same speed
- D.intensity of flash of lightning is very high during thunderstorm
Show answer
The flash and the clap are produced at the same instant by the same discharge.
Read the full explanation →