Question

Which of the following statements is/are true in the case of waves?
A. Transverse vibrations are set on the string of a guitar.
B. As compared to light, a sound wave produced on the moon will take about 106 times longer to reach the earth.
C. A sound note of wavelength $1cm$ in air cannot be heard by a man.
D. Sound travels faster in water than in air.

Answer 1

In this question we must have a concept of sound waves, a transverse wave medium in which the sound waves travel. After having concepts of these topics one can easily answer this question. Firstly, we will check all the options one by one and as per the concept we will take the correct option out.

Complete Step By Step Answer:
We know that A transverse wave has oscillations that are perpendicular to the wave's advance direction. A longitudinal wave, on the other hand, travels in the direction of its oscillations.
Let’s check the option A.
We know that in a guitar, the waves travel sideways the string. And the sound is created by the vibration of the string perpendicular to the path of propagation. So, we can easily say that this option is correct.
Now let’s check the option B.
As we know that the sound waves will not be able to reach the surface of the earth from the moon as there is no medium in the moon and space and sound needs a medium to travel. So, we can say that this option is not true.
Now let’s check the option C.
As we know, the frequency of sound is equal to the wavelength Speed​which is $0.01330 = 33000Hz$ . And we know that the range of a human ear is $20Hz = 20000Hz$ . So, we can say that this option is also true.
Now let’s check the option D.
Let’s take an example of a bottle filled with air and another with water. As there are more particles in the bottle containing water which is more than 800 times more particles as a result sound waves travel faster in water than that of water. So, this option is correct.
In conclusion option A, C, D is the correct option.

Note:
Don’t forget to check all the options as this question has multiple correct options and the nature of sound waves is that they travel in a straight line. This is due to the fact that when it travels through air, the particles move back and forth, causing the air pressure to vary, resulting in the formation of a longitudinal wave.
One of the most essential characteristics of sound waves is that they can only travel in a medium. There is a simple experiment that can be used to demonstrate this: In a vacuum-sealed jar, an electrical bell is installed. When the bell rings, the person standing outside is unable to hear it since sound travels via no medium.