Question

Sound cannot travel in vacuum
A) True
B) False

Answer 1

Let us first understand what is meant by sound. When the objects vibrate,the waves are produced and traversed in the medium. When it reaches our eardrum, the human brain interprets it as sound.

Complete answer:
Sound is formed by the vibration of the particles in the medium like air, water etc through which the waves travel. Sound is also defined as the longitudinal wave that is a combination of compression and relaxation. Vacuum is an enclosed place in which there are no molecules or matter. Therefore sound cannot travel through vacuum where there is no molecule or atom to induce vibrations.

Additional information:
Sound is defined by the following attributes
Wavelength: it is the distance between two adjacent compression or relaxation. SI unit is lambda.
Amplitude: it is the maximum distance or displacement travelled by the vibrating particle from its equilibrium position. Si unit is decibels.
Frequency: the number of vibrations per second or it is the reciprocal of time period.SI unit is hertz
Time Period:it is the time taken by the wave to complete one cycle. SI unit is second.
Velocity /speed: it is the distance travelled by the wave per unit time. SI unit is meter per second.

Hence the correct answer is (A) true.

Note: Vacuum has lower pressure compared to the atmospheric pressure. Sound waves are mechanical waves which need a medium to travel whereas electromagnetic waves do not need a medium for propagation and hence they can travel through vacuum.