Waves, Sound and Light

Question 1

`What is a pulse?

Answer 1

A single disturbance in a medium.

Question 2

What is a transverse pulse?

Answer 2

A pulse in which the particles of the medium move at right angles to the direction of motion of the pulse.

Question 3

Define amplitude

Answer 3

The maximum disturbance of a particle from its rest (equilibrium) position.

Question 4

What is the principle of superposition?

Answer 4

The algebraic sum of the amplitudes of two pulses that occupy the same space at the same time.

Question 5

Define constructive interference

Answer 5

The phenomenon where the crest of one pulse overlaps the crest of another to produce a pulse of increased amplitude.

Question 6

Define destructive interference

Answer 6

The phenomenon where the trough of one pulse overlaps with the trough of another, resulting in a pulse of reduced amplitude.

Question 7

What is superposition?

Answer 7

Diagram

Question 8

What is a transverse wave?

Answer 8

A wave in which in which the particles of the medium vibrate at right angles to the direction of motion of wave. A transverse wave is a succession of transverse pulses.

Question 9

Define wavelength

Answer 9

The distance between two successive points in phase.

Question 10

Define frequency

Answer 10

The number of wave pulses per second

Question 11

What is period?

Answer 11

The time taken for one complete wave pulse

Question 12

Define amplitude

Answer 12

The maximum displacement of a particle from its equilibrium position

Question 13

What is a crest?

Answer 13

Highest point (peak) on a wave

Question 14

What is a trough?

Answer 14

Lowest point on a wave

Question 15

Explain what in phase means

Answer 15

Two points in phase are separated by a whole number ( 1;2;3….) multiple of complete wavelengths

Question 16

Explain what out of phase means?

Answer 16

Points that are not separated by a whole number multiple of complete wavelengths

Question 17

What is wave speed?

Answer 17

The distance travelled by a point on a wave per unit time

Question 18

What is a longitudinal wave?

Answer 18

A wave in which the particles of a medium vibrate parallel to the direction of motion of the wave.

Question 19

Define a compression

Answer 19

A region of high pressure in a longitudinal wave.

Question 20

Define a rarefaction

Answer 20

A region of low pressure in a longitudinal wave

Question 21

What is a sound wave?

Answer 21

Sound waves are created by vibrations in a medium in the direction if propagation. These vibrations cause a regular variation in pressure in the medium.

Question 22

What kind of wave is a sound wave?

Answer 22

Longitudinal

Question 23

What is a echo?

Answer 23

Reflections of sound waves.

Question 24

What is pitch?

Answer 24

The frequency of a sound wave. Pitch is the effect produced in the ear due to the sound of a particular frequency. Pitch is directly proportional to frequency.

Question 25

What is the loudness of sound?

Answer 25

Both the amplitude of a sound wave and the sensitivity of the human ear. Loudness is a subjective term describing the strength of the ears perception of a sound. Loudness is directly proportional to amplitude.

Question 26

What is the quality of sound?

Answer 26

The waveform as it appears to the listener. Two notes of the same pitch and loudness, played on different instruments do not sound the same because the wave forms are different and therefore differ in quality and tone.

Question 27

Dual particle/wave) nature of electromagnetic radiation.

Answer 27

Some aspects of the behaviour of electromagnetic radiation can best be explained using a wave model and some aspects can best be explained using a particle model.

Question 28

What is the source of electromagnetic waves?

Answer 28

An accelerating charge.

Question 29

How does an electromagnetic wave propagate?

Answer 29

It propagates when an electric field oscillating in one plane produces a magnetic field oscillating in a plane at right angles to it, which produces an oscillating electric field, and so on.

Question 30

Ultrasound

Answer 30

describe sound with frequencies higher than 20kHz up to bout 100 kHz as ultrasound

Question 31

Explain how an image can be created using ultrasound

Answer 31

When a wave encounters a boundary between two medians, part of the wave is reflected, part is absorbed and part is transmitted.

Question 32

What are the medical benefits and uses of ultrasound

Answer 32

Safety, diagnosis, treatment and pregnancy

Question 33

List the properties of electromagnetic waves?

Answer 33

Originate from accelerating electric charges Propagate as electric and magnetic fields that are perpendicular to each other Can travel through a vacuum Have a speed of 3 x 10 to the 8 ms -1

Question 34

Give an example of each type of electromagnetic radiation

Answer 34

Gamma rays- nuclear explosions X-rays- X rays check for broken bones Ultraviolet light- the sun Visible light- the sun Infrared- remote controls Microwave- microwaves Radiowaves- radio

Question 35

What is a photon

Answer 35

A packet of energy found in light