Light and sound

Question 1

Light is a wave which always travels in …..

Answer 1

A straight line

Question 2

Which travels faster light or sound?

Answer 2

Light

Question 3

Give an example which demonstrates that light travels faster than sound

Answer 3

In a race you see the smoke from the starting pistol before you hear the bang.

Question 4

Whereabouts does light travel fastest?

Answer 4

In a vacuum

Question 5

State the speed of light.

Answer 5

3 x 10⁸

Question 6

How long does it take the light from the sun to reach the Earth?

Answer 6

8.3 minutes

Question 7

What is a vacuum

Answer 7

A space which contains nothing - no particles at all even air
Space is a vacuum

Question 8

Nothing travels faster than what in a vacuum?

Answer 8

ilght

Question 9

What happens when light hits a prism?

Answer 9

The white light splits into the light spectrum

Question 10

State the colours of the light spectrum in the order they come out of a prism

Answer 10

Red
Orange
Yellow
Green
Blue
Indigo
Violet

Question 11

What do we see when light from the sun hits raindrops

Answer 11

A rainbow

Question 12

What causes a rainbow?

Answer 12

Light from the sun hits drops of rain, the light splits into the light spectrum.

Question 13

State another name for a light wave

Answer 13

A light ray

Question 14

Explain how we see objects

Answer 14

A light source is needed which can be sunlight or artificial light
The light is reflected off non luminous objects such as people or furniture
Some of that reflected light goes into our eyes allowing us to see

Question 15

What is a mirror?

Answer 15

An object with a smooth shiny surface which reflects light.

Question 16

What is a plane mirror

Answer 16

A mirror which is flat and reflects light back at the same angle giving a clear reflection

Question 17

State the law of reflection

Answer 17

Angle of incidence = Angle of reflection
Angle i = Angle r

Question 18

What is this a picture showing?

Answer 18

The law of reflection in a plane mirror

Question 19

Give 2 practical examples of mirrors used in transport

Answer 19

1. The rearview mirror on a car allows the driver to see vehicles behind them
2. A mirror on a sharp bend or concealed entrance can allow a driver to see what is coming.

Question 20

Explain how a periscope uses mirrors to allow you to see around a corner.

Answer 20

A tube contains two mirrors each set at 45 degrees. The light reflects from one mirror to the other and into the eye

Question 21

What is refraction

Answer 21

It is where light bends as it crosses a boundary between different substances

Question 22

What is a transparent material?

Answer 22

Something which light can travel through

Question 23

What is an opaque material?

Answer 23

Something which light cannot travel through

Question 24

What is a medium?

Answer 24

It is something that waves can travel through eg light waves or sound waves

Question 25

If light hits a medium at an angle. How does the light bend when it travels from a less dense medium to a more dense medium?
Eg from air into glass

Answer 25

It bends towards the normal
The normal is perpendicular to the two mediums (90 degrees)

Question 26

If light hits a medium at an angle. How does the light bend when it travels from a more dense medium to a less dense medium?
eg from glass to air

Answer 26

It bends away from the normal
The normal is perpendicular to the two mediums (90 degrees)

Question 27

If light hits a different medium in a straight line does it bend or travel through in a straight line

Answer 27

A straight line

Question 28

Why does sound need a medium to travel through?

Answer 28

It needs something to pass on the sound vibrations?

Question 29

Can you hear sound in a vacuum?

Answer 29

NO because sound needs something to pass on the sound vibrations?

Question 30

Describe the bell jar demo for sound

Answer 30

A bell is put in a bell jar which is attached to a vacuum pump
Whilst there is air in the jar the bell can be heard ringing because the air vibrates and the sound waves can travel to our ears
As the air is sucked out of the jar there is no air to vibrate so the sound cannot be heard.

Question 31

What does an oscilloscope show

Answer 31

The amplitude and frequency of a sound wave

Question 32

What is the amplitude of a wave?

Answer 32

It is the height of the wave
It shows the amount of energy the wave has
The higher the amplitude the louder the sound

Question 33

What is the frequency of a wave?

Answer 33

It is the number of waves which pass a point in one second
High frequency gives a high pitched note
Lower frequency notes are lower pitch

Question 34

How do we hear sounds?

Answer 34

Question 35

What is the name of the nerve which carries messages to the brain from the cochlea?

Answer 35

Auditory nerve

Question 36

What is audible range?

Answer 36

It is the range of frequencies you can hear

Question 37

What is the average audible range for humans?

Answer 37

20 to 20,000 Hertz (Hz)

Question 38

What is frequency measured in?

Answer 38

Hertz (Hz)

Question 39

What is loudness measured in?

Answer 39

decibels (dB)

Question 40

State some possible causes of poor hearing

Answer 40

1. wax blocking ears
2. nerve damage
3. damage caused by illness or injury
4. old age

Question 41

Hearing can be damaged by sounds above……

Answer 41

85 dB

Question 42

Sudden loud noises such as explosions can cause what sort of damage to the ears?

Answer 42

1. Burst the ear drum
2. Damage the ear bones

Question 43

How can loud noises for extended periods of time can damage the ears

Answer 43

They damage the hairs in the cochlea