Waves

Question 1

What is a transverse wave?

Answer 1

Oscillations are perpendicular to the direction of travel

Question 2

What is a longitudinal wave?

Answer 2

Oscillations are parallel to the direction of travel

Question 3

What is amplitude?

Answer 3

Maximum displacement from the normal position

Question 4

What is frequency?

Answer 4

Number of waves per second

Question 5

What is wavelength?

Answer 5

Distance from crest to next crest

Question 6

What is Time Period?

Answer 6

Time for wave to complete one oscillation

Question 7

Equation: Wave speed v =

Answer 7

v = frequency x wavelength

Question 8

Equation: Frequency f =

Answer 8

f = 1/time period
f = 1/T

Question 9

Give an example of a longitudinal wave.

Answer 9

Sound

Question 10

Give an example of a transverse wave.

Answer 10

Electromagnetic spectrum

Water waves

Question 11

What is the Doppler effect?

Answer 11

When the source of a wave moves towards the observer, observed frequency increases.
When a source moves away, observed frequency decreases.

Question 12

What do all waves do?

Answer 12

Transfer energy and information without transferring matter.

Question 13

List the electromagnetic spectrum in order of decreasing wavelength and increasing frequency.

Answer 13

Radio
Microwaves
Infra Red
Visible Light (ROYGBIV)
Ultra violet
X Rays
Gamma rays

Question 14

Give a use and hazard of gamma rays?

Answer 14

use: sterilising food and medical equipment
hazard: cancer and cell mutations

Question 15

Give a use and hazard of X rays?

Answer 15

use: observing internal structures like bones
hazards: cancer and cell mutations

Question 16

Give a use and hazard of ultra violet.

Answer 16

use: fluorescent lamps, tanning lamps, checking counterfeit money
hazards: damage tovsurface cells of the skin and blindness

Question 17

Give a use and hazard of infra red.

Answer 17

use: heaters and night vision
hazards: skin burns

Question 18

Give a use and hazard of microwaves.

Answer 18

use: cooking and satellite communications/moblie phones
hazards: internal heating of body tissues

Question 19

Give a use of visible light.

Answer 19

photography

Question 20

Give a use of radio waves.

Answer 20

broadcasting and communications

radar

Question 21

What properties do all electromagnetic waves have in common?

Answer 21

all transverse waves
all travel in a vacuum
all travel at same speed in a vacuum (300 000 000m/s)

Question 22

What is the Law of reflection?

Answer 22

Angle of incidence = angle of reflection

Question 23

What must you remember when measuring the angles of incidence and reflection?

Answer 23

measured between the ray and the normal

Question 24

Equation for refective index n =

Answer 24

n = sin i/ sin r

Question 25

What are the 2 conditions for Total internal reflection to occur?

Answer 25

1. Ray travelling from a higher refractive index to a lower refractive index 2. at an angle greater than the critical angle

Question 26

What is the critical angle?

Answer 26

Angle at which the ray refracts at 90 degrees along the boundary. Angle greater than critical and total internal reflection occurs.

Question 27

For critical angle c sin c =

Answer 27

sin c = 1 / n

Question 28

Refraction is the change of direction of a wave what changing speed. Travelling from less optically dense to more optically dense medium, what happens to speed, wavelength and frequency?

Answer 28

less dense to more dense: speed decreases wavelength decreases frequency stays the same

Question 29

Refraction is the change of direction of a wave what changing speed. Travelling from more optically dense to less optically dense medium, what happens to speed, wavelength and frequency?

Answer 29

more dense to less dense: speed increases wavelength increases frequency stays the same

Question 30

What is the frequency for human hearing?

Answer 30

20 to 20 000 Hz

Question 31

Pitch of sound is related to ....

Answer 31

frequency

Question 32

Loudness of sound is related to ....

Answer 32

amplitude

Question 33

What equipment do we use to investigate sound waves?

Answer 33

mircrophone connected to an oscilloscope

Question 34

What equipment do we need to investigate speed of sound?

Answer 34

``` Two microphones 2 m apart Make sound with hammer First microphone starts timer Second timer stops microphone Repeat and find an average Speed = distance / time ```

Question 35

What is a wavefront?

Answer 35

Line of points in phase with each other (move together)

Question 36

Waves transfer energy and information without ....

Answer 36

transferring matter.

Question 37

Is light longitudinal or transverse?

Answer 37

transverse

Question 38

Is sound longitudinal or transverse?

Answer 38

longitudinal

Question 39

Name two uses of total internal reflection

Answer 39

fibre optics in cable tv and endoscopes | prism binoculars

Question 40

All waves can be .....

Answer 40

All waves can be reflected and refracted