Light waves

Question 1

What is a wave?

Answer 1

Waves are one of the ways in which energy may be transferred between energy stores.

Question 2

How could you describe a wave?

Answer 2

Waves can be described as oscillations, or vibrations about a rest position.

Question 3

What are mechanical waves?

Answer 3

Mechanical waves: are waves that require a medium e.g. air/water. This means that they have to have some sort of matter to travel through.

Question 4

What are electromagnetic waves?

Answer 4

Electromagnetic waves: are waves that can travel through a vacuum (empty space). They don’t need a medium or matter.

Question 5

Give an example of a longitudinal wave.

Answer 5

Sound waves are longitudinal waves.

Question 6

Give an example of a transverse wave.

Answer 6

Light waves are transverse waves.

Question 7

What is the direction of travel of the vibrations in a longitudinal wave?

Answer 7

In longitudinal waves, the vibrations are parallel to the direction of wave travel.

Question 8

What is the direction of travel of the vibrations in a transverse wave?

Answer 8

In transverse waves, the vibrations are at right angles to the direction of wave travel.

Question 9

What is the peak of a wave?

Answer 9

Peak - the highest point of a wave (above the rest position).

Question 10

What is the trough of a wave?

Answer 10

Trough - the lowest point of a wave (below the rest position).

Question 11

What is meant by the ‘amplitude’ of a wave?

Answer 11

Amplitude - the distance from the middle of a wave to the top (peak) or bottom (trough) of a wave. The ‘loudness’ of a sound.

Question 12

What is a wavelength?

Answer 12

Wavelength - the distance from one point on a wave to the same point on another wave. Usually measured from peak to peak, or trough to trough

Question 13

What is frequency of a wave?

Answer 13

Frequency - the number of waves passing a particular point each second. Frequency is measured in hertz (Hz). The pitch of a note depends on it’s frequency.

Question 14

What is the difference between transparent and translucent materials?

Answer 14

A transparent material lets almost all the light pass through whereas a translucent material only allows some of the light through.

Question 15

Can light travel through an opaque material?

Answer 15

No, an opaque material does not allow light to pass through. e.g. wooden table, mirror

Question 16

What is a luminous object?

Answer 16

Luminous objects are objects that give out their own light e.g. the sun, candle flame.

Question 17

Define specular reflection

Answer 17

Reflection from a smooth, flat surface is called specular reflection. This is the type of reflection that happens with a flat mirror.

Question 18

Define diffuse scattering in terms of reflection

Answer 18

If a surface is rough, diffuse reflection happens. Instead of forming an image, the reflected light is scattered in all directions.

Question 19

What does the law of reflection state?

Answer 19

‘’when light is reflected from a smooth surface e.g. a mirror, the angle of incidence is equal to the angle of reflection.’’

Question 20

What is meant by the term ‘refraction’ of light.

Answer 20

Refraction of light is the BENDING of light when it passes from one medium (e.g. air) to another medium (e.g. water).

Question 21

The image shows a transverse wave. What is label W the image?

Answer 21

Peak/crest

Question 22

The image shows a transverse wave. What is label Y the image?

Answer 22

Trough

Question 23

The image shows a transverse wave. What is label Z the image?

Answer 23

Wavelength

Question 24

The image shows a transverse wave. What is label X the image?

Answer 24

Amplitude

Question 25

What are the 7 colours of white light?

Answer 25

Red, orange, yellow, green, blue, idigo and violet

Question 26

When white light passes through a _____________ it splits into it’s 7 different colours.

Answer 26

Prism

Question 27

The splitting of white light when it passes through a prism is called _____________.

Answer 27

Dispersion