Waves, Sound and Light - Topic 1, Waves

Question 1

Why is it that a circular wave produced on a tilted ripple tank forms an oval shape and not a perfect circle?

Answer 1

As the ripple tank is tilted, more water is on one side than the other, meaning that one side is deeper than the other. This means that the waves on one side will travel faster than those on the other side, forming an irregular circle.

Question 2

What is the human range of hearing?

Answer 2

Human beings hear only sounds with frequencies from about 20 Hz to 20,000 Hz, although the upper limit decreases with age.

Question 3

Are sound waves longitudinal or transverse waves?

Answer 3

Longitudinal

Question 4

What produces sound?

Answer 4

Vibrations

Question 5

Definition of an echo

Answer 5

If the reflecting surface is nearer than 15m, the echo joins up with the original sound which then seems to be prolonged. This is called reverberation.

Question 6

What are ultrasonic waves?

Answer 6

Sound waves with frequencies above 20 KHz are called ultrasound waves

Question 7

What is the speed of sound in air?

Answer 7

330 m/s

Question 8

What is the speed of sound in water?

Answer 8

1400 m/s

Question 9

What is the speed of sound in concrete?

Answer 9

5,000 KHz

Question 10

What is the speed of sound in steel?

Answer 10

6000 m/s

Question 11

Name some of the applications of echoes in industry

Answer 11

Ships use ultrasonic waves to measure the depth of the sea and to detect shoals of fish

In industry ultrasonic waves are used to reveal flaws in welded joints

Reverberation is desirable in a concert hall to stop it sounding ‘dead’, but too much causes confusion. Modern concert halls are designed for the optimum amount of reverberation. Seats and some wall surfaces are covered with sound-absorbing material.

Question 12

What properties of sound suggest it as a wave motion?

Answer 12

Waves can be reflected, and so can sound to form an echo.

Question 13

What is a transverse wave?

Answer 13

A progressive transverse wave is an oscillation that travels at a right angle to wave propagation

Question 14

What is a longitudinal wave?

Answer 14

A longitudinal wave is an oscillation that travels parallel to the direction of wave propagation

Question 15

What is a progressive wave?

Answer 15

A progressive wave is a mechanical wave motion that requires a medium or matter for the oscillations/vibrations to travel through

Question 16

List the features of a progressive wave

Answer 16

A progressive wave can be reflected, refracted and diffracted, and requires a medium to travel through

Question 17

What is the frequency of a wave?

Answer 17

The frequency (f) is the number of complete oscillations made in one second by a particle in the wave train

Question 18

What factors affect the speed of the wave?

Answer 18

Medium
Frequency
Wavelength

Question 19

f = Number of complete waves per second
lambda = Wavelength of waves

Therefore, fxw = …

Answer 19

Distance moved by wave train in 1 second

Otherwise known as speed (m/s)

Question 20

Amplitude definition

Answer 20

The amplitude (a) is the height of a crest or depth of a trough measured from the undisturbed position of what is carrying the wave

Question 21

Recall the echo principle formula

Answer 21

V = 2nd/t