Question

Which of the following statements is WRONG?
A. Changes in air temperature have no effect on the speed of sound
B. Changes in air pressure have no effect on speed of sound
C. The sound of speed in water is higher than in air
D. The speed of light in water is lesser than in air

Answer 1

Hint:In this question, we have to find the wrong statement. For that we have to go through every statement. On taking the glimpse of all the options we come to know that all the options are being related to the sound. Now we have to revise all the properties of sound.

Complete answer:
Reading all the options one by one in order to find the wrong statement:
Option A.: Changes in air temperature have no effect on the speed of sound
Revising the fact about air temperature that the speed of sound in air is directly proportional to the square-root of its absolute temperature. $V \propto \sqrt T $. Hence, the given statement is wrong. But we will go through every option just to prove that our assumption is correct or not.

Properties of sound are:
-It travels in a straight line and travels as a wave.
-Sound is a form of energy and needs a material medium for its propagation.
-Velocity of sound in air and water is given by:
${v_{air}} = \sqrt {\dfrac{{{\gamma _{air}}RT}}{M}} $
$\Rightarrow{v_{water}} = \sqrt {\dfrac{{{\gamma _{water}}p}}{\rho }} $
Velocity of sound in air is independent of pressure. This concludes the option B.

Speed of sound depends on density. Hence higher the density of the medium, faster the sound travels.This concludes the option C.Now, coming to the speed of light as we all know when light travelling in air enters a transparent medium such as glass or water, its speed is reduced and that speed is dependent on the refractive index.Refractive index for air is lowest. Hence, speed of light in air is maximum which concludes that speed of light in water is lesser than in air which proves our option D.

Hence, the wrong statement from the above options is A.

Note:Speed of sound is $1235$ kilometers per hour or $330$ meters per second in dry air and was invented by Jean-Baptiste Biot in $1808$. Sound is a wave that propagates by making the neighboring particles interact with one another so depends on the density of the material.