waves

Question 1

waves

Answer 1

Waves are oscillations or vibrations.
All waves transfer energy.
The matter a wave passes through does not move from its position.
You can see information about a wave on an oscilloscope.

Question 2

Wavelength

Answer 2

the distance between a point of a wave to the same point on the next wave.

Question 3

Longitudinal waves

Answer 3

Longitudinal waves are oscillations which occur parallel to the direction of travel.
In a longitudinal wave, the particles come close together and then push apart.
When the particles are close together, this is called compression.
When the particles are far apart, this is called a rarefaction.
An example of a longitudinal wave is a sound wave.
Longitudinal waves are also called pressure waves.

Question 4

Transverse waves

Answer 4

Transverse waves occur when the oscillations are perpendicular or at right angles (90°) to the direction of travel.
Examples of transverse waves include water waves and electromagnetic waves.

Question 5

Electromagnetic waves

Answer 5

Electromagnetic waves are transverse waves.
They are able to travel through a vacuum (such as space) so do not need a medium to travel through.
They range in wavelength size. The largest to smallest wavelength waves are:
Radio waves.
Microwaves.
Infra-red.
Visible Light.
Ultra-Violet.
X-Rays.
Gamma Ray.

Question 6

Sound Wave

Answer 6

they are longitudinal waves. The particles compress, and then push apart, leading to an area of high pressure which moves in space, and an area of low pressure which follows it.

Question 7

Waves

Answer 7

A wave is a vibration that transfers energy.

Question 8

Types of Wave

Answer 8

There are two types of waves: transverse and longitudinal.

Question 9

Observing Waves

Answer 9

Many waves cannot be seen with the naked eye. They are invisible. We are able to see and study water waves.

Question 10

Water waves

Answer 10

Water waves are transverse waves.
In a small pond, these waves are called ripples.
Waves moving up and down can be described as undulations.
The tallest water wave ever recorded happened in 1958 in Alaska. It was over 100ft tall.

Question 11

Superposition

Answer 11

Waves can be added together or cancel each other out.
This is called superposition.
If waves superpose by adding together, they will get bigger and increase amplitude.
Waves will cancel each other out if, when the waves combine, one wave’s peak meets the other wave’s trough.

Question 12

Calculating Wave Speed

Answer 12

If we know the frequency of the wave and the wavelength, we can work out the speed it travels at. Light travels about one million times faster than sound.

Question 13

Calculating wave speed

Answer 13

Wave speed is calculated using the equation:
Wave speed = frequency × wavelength.
Wave speed is measured in m/s.
Frequency is measured in hertz (Hz).
Wavelength is measured in metres (m).

Question 14

Speed of sound and light

Answer 14

Light travels at 300,000,000 m/s.
Sound travels at 340 m/s in air.
This is why we can see lightning before we hear thunder.

Question 15

Ripples in a Pond

Answer 15

Water waves are transverse waves. In a small pond, these waves are called ripples.

Question 16

Light Waves

Answer 16

Light is a form of electromagnetic radiation that travels as waves. The Earth gets its light from our nearest star, The Sun.

Question 17

Light

Answer 17

Travels as transverse waves.
Light is electromagnetic radiation.
Light can travel through a vacuum.
It takes about eight minutes for the Sun’s light to reach us traveling at 300,000,000 m/s.

Question 18

Light through objects

Answer 18

Objects that do not allow light to transmit or pass through are called opaque.
Glass and other see-through objects are transparent because light can be transmitted through them.
Translucent objects scatter light. So not all the light is transmitted, such as in privacy windows in bathrooms and walk-in showers.

Question 19

Opaque

Answer 19

Don’t allow light to pass through

Question 20

Translucent

Answer 20

Scatter light that passes through

Question 21

Transparent

Answer 21

Allow all light to pass through

Question 22

Reflection

Answer 22

Light can bounce off surfaces. We call this reflection.

Question 23

Reflection

Answer 23

We see our image in a mirror because of reflection.
Reflection from a smooth surface, like a mirror or polished surface, is called specular reflection.
If light is reflected from a rough surface, this is called diffuse scattering.
We do not see an image in diffuse scattering because light is scattered in lots of different directions.

Question 24

A mirror image

Answer 24

A flat mirror is called a plane mirror.
We can describe a mirror image as:
Virtual - we call an image in a mirror ‘virtual’ as the image isn’t really there. If you move away so should your image.
Upright – the image is the same way up as the object it is reflecting.
Equal distance – the object’s distance to the mirror will be the same as the image’s distance from the mirror.

Question 25

Laterally inverted image

Answer 25

We can also describe a mirror image as laterally inverted – if you hold up your left hand to wave at a mirror, your reflection waves its right hand.
This is the reason why ‘ambulance’ and ‘fire’ are written backwards on emergency vehicles, so when you look in your car mirror, the writing will appear the right way around.

Question 26

Law of reflection

Answer 26

The law of reflection states:
The angle of incidence equals the angle of reflection.
We are able to see objects as light reflects off objects into our eyes.
When reflection happens, it always follows the law of reflection

Question 27

Drawing a Reflected Image

When drawing a reflected image, you must always follow the following instructions:

Answer 27

Always use a ruler and pencil
Light travels in straight lines after all.

Use arrows to show direction
Light rays must have an arrow on the light ray to show the direction of the light.

Draw a normal
A normal line is drawn at 90° from the mirror - this is normally dotted.
The incident ray is the light that hits the mirror at the normal.
The reflected ray is the light that reflects off the mirror.

Remember the law of reflection!:
The angle of incidence is the angle between the incident ray and the normal.
The angle of reflection is the angle between the reflected ray and the normal.
The two angles should be the same.

Question 28

how to work out stuff

Answer 28

Light travels between two asteroids in two seconds. How far apart are they?
1
Remember the speed of light
The speed of light is 300,000,000 m/s
2
Remember the equation for distance
Distance = speed × time
3
Calculate the distance
Distance = 300,000,000m/s × 2 = 600,000,000m

Question 29

Peak or crest

Answer 29

the top of a wave.

Question 30

Trough

Answer 30

the bottom of a wave.

Question 31

Amplitude

Answer 31

the distance from the middle to the crest or trough of the wave.

Question 32

Frequency

Answer 32

the number of waves that travel past a single point every second. Measured in Hertz (Hz).

Question 33

compression.

Answer 33

When the particles are close together

Question 34

rarefaction

Answer 34

When the particles are far apart