Year 10 - Waves

Question 1

What is a wave?

Answer 1

A wave transfers energy from one place to another without any overall transfer of matter

Question 2

How is a wave created?

Answer 2

In order to make a wave something needs to vibrate.

Question 3

What is a Medium?

Answer 3

The thing that vibrates. This can be either a collection of particles or an electromagnetic field.

Question 4

What evidence is there that it is the wave that travels and not matter?

Answer 4

When a sound wave travel through the air the air particles do not travel from one place to another. The particles vibrate around a fixed point.

Question 5

What is a transverse wave?

Answer 5

A wave where the vibrations are at right angles (perpendicular) to the direction of energy transfer. This causes peaks and troughs.

Question 6

What waves are transverse?

Answer 6

Water
Electromagnetic radiation such as visible light

Question 7

What does it mean to oscillate?

Answer 7

The repeated and regular fluctuations, above and below the same position

Question 8

What is a longitudinal wave?

Answer 8

Vibrations are in the same direction (parallel) to the direction of travel. It causes compression and rarefaction.

Question 9

What is a compression?

Answer 9

In a longitudinal wave where the particles are close together.

Question 10

What is a rarefaction?

Answer 10

In a longitudinal wave where the particles are far apart.

Question 11

What is the definition of frequency?

Answer 11

The number of vibrations per second. Its measured in Hertz (Hz).

Question 12

What is the definition of time period?

Answer 12

The time for one wave to pass a point. Its measured in Seconds.

Question 13

What is the definition of wavelength?

Answer 13

The distance from a point on a wave to the same point on the next wave. Its measured in metres.

Question 14

What is the amplitude?

Answer 14

The distance between the peak or trough and the position of the medium at rest.

Question 15

What is the crest?

Answer 15

The highest part of a wave

Question 16

What is the trough?

Answer 16

The lowest part of the wave.

Question 17

What is the relationship between time period and frequency?

Answer 17

T= 1/f

Question 18

What is wavespeed?

Answer 18

Wave speed is the speed at which energy is transferred through the medium.

Question 19

How do you measure the speed of sound in the air?

Answer 19

Person one should stand a large distance away from person two and make an obvious visible sound. The distance between them should be measured with a tape measure. Person two should start their stopwatch when they see the sound being made and stop it when they hear it. Speed = Distance/Time

Question 20

What is the relationship between wave speed, frequency and wavelength?

Answer 20

Wave speed= Wavelength x Frequency

Question 21

How can you measure the speed of ripples on water surface?

Answer 21

Using a ripple tank you can measure the distance across ten waves using a ruler and then divide by 10 to find 1 wavelength. You can read the frequency from the signal generator that is driving the ripple tank making the waves. the speed can then be calculated using speed = frequency x wavelength.

Question 22

How would you determine the speed of waves on a string?

Answer 22

Stretch a string over a pulley using masses. Use a frequency generator to generate a wave in the string. Measure the wavelength when a clear wave is shown and note the frequency on the generator. Use wave-speed equation.

Question 23

What is the difference between diffuse and specular reflection?

Answer 23

Specular reflection happens when light is incident on smooth surfaces and parallel rays of incident light are reflected in a predictable manner and remain parallel to each other upon reflection. Diffuse reflection happens on a rough surface and parallel rays of light do not remain parallel to each other on reflection and are scattered in different directions.

Question 24

What is the law of reflection?

Answer 24

The angle of incidence is equal to the angle of reflection

Question 25

What is a virtual image?

Answer 25

A virtual image is one from which the light rays appear to come but don’t actually come from the image.

Question 26

What is a real image?

Answer 26

A real image is one where the light rays come from the image

Question 27

What is refraction?

Answer 27

Refraction is the change in speed of a wave when it reaches the boundary between two different material. It happens because material have different optical densities. It causes the wave to change direction.

Question 28

What happens to frequency and wavelength when a wave undergoes refraction?

Answer 28

When a wave undergoes refraction it’s frequency doesn’t change. This is because the source of the wave doesn’t change at all. The wave length will increase if a wave speeds up.

Question 29

What effect foes the refraction of light lead to?

Answer 29

Refraction of light at water/air boundaries causes objects to appear closer to the water surface than they actually are.

Question 30

What happens to parallel rays of light when they enter a convex lens?

Answer 30

In a convex lens parallel rays from a distant source of light are made to converge at a point known as the focal point, a distance called the focal length from the centre of the lens.

Question 31

What happens to parallel rays of light when they enter a concave lens?

Answer 31

In a concave lens parallel rays of light are made to diverge away from the lens. The focal point is on the same side of the lens as the object.

Question 32

How to calculate maginifaction?

Answer 32

Magnification = image height/ object height

Question 33

What happens to white light when it is shone through a prism?

Answer 33

When white light is directed through a prism/ the separate colours of the spectrum are seen. This is called dispersion and happens because different colour (wavelength) light changes speed by different amounts.

Question 34

Why do opaque objects appear the colour they do?

Answer 34

Coloured objects reflect only the wavelengths (colours) of light that they appear and absorb all others. White objects reflect all wavelengths, black objects absorb all wavelengths.

Question 35

What is a transparent and translucent object?

Answer 35

They both transmit light that is incident on them but translucent object do so only partially.

Question 36

What is a filter?

Answer 36

A filter only allows light of the wavelengths corresponding to it’s colour to pass through it (be transmitted) all other wavelengths are absorbed.

Question 37

What happens to the colour of an object if it is viewed through a colour filter?

Answer 37

If the filter allows the wavelength of light corresponding to the object to pass it will look the colour it is. If the filter does not allow the wavelength of light corresponding to the object to pass it will look black.