Waves incl sound

Question 0

What is a transverse wave?

Answer 0

One in which the oscillations take place at right angles to the direction the wave is traveling.

Question 1

What is a longitudinal wave?

Answer 1

A wave in which the oscillations are parallel to the direction the wave is travelling.

Question 2

What are electromagnetic waves classed as?

Answer 2

Transverse waves

Question 3

What are sound waves classed as?

Answer 3

Longitudinal

Question 4

What are water waves classed as?

Answer 4

Transverse but they are actually transverse and longitudinal.

Question 5

What is the amplitude of a wave?

Answer 5

The distance from the maximum movement of particles to the resting position (the dotted line)

Question 6

What is a wave?

Answer 6

A mean of transferring energy from place to place.

Question 7

What is the wavelength of a wave?

Answer 7

The distance from a particular point on a wave and the same point on the next wave.

Question 8

What is the frequency of a wave?

Answer 8

The number of waves produced each second. Measured in hertz.

Question 9

What is the time period of a wave?

Answer 9

The time it takes to produce one wave.

Question 10

What is an oscillation?

Answer 10

A repetitive ‘to and fro’ movement. E.g a mass ‘bouncing’ up and down on a spring.

Question 11

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

Answer 11

Wave speed = frequency x wavelength

V = f x l (Greek l)

Question 12

What is the relationship between frequency and time period?

Answer 12

Frequency = 1/time period
f = 1/T

Question 13

What is T measured in?

Answer 13

Seconds

Question 14

What happens when plane waves reflect off a concave barrier?

Answer 14

The waves reflect off twice as curved, they are brought to a focus but these is no change in wavelength.

Question 15

Uses of visible light fluorescence

Answer 15

-highlighters
-security markers on money
-forensics
-teeth whitening
-washing powder
The ozone layer absorbs UV rays.

Question 16

What are ultraviolet waves?

Answer 16

Waves with a harmful ionising effect, they have high energy. Some chemicals absorb UV light and emit visible light fluorescence so are used in fluorescent lighting.

Question 18

Uses of X-rays?

Answer 18

Observing the internal structure of objects and materials and medical applications

Question 18

What is a CAT scan?

Answer 18

Many x rays taken from different angles and the images combined produce a 3D image that can be ‘sliced’.

Question 19

What are X rays and how are they produced?

Answer 19

X-rays pass through skin, cartilage and tissue but not through bone so a sensitive material on the other side of a source of x rays will emit an image.
Produced by firing electrons at a metallic tungsten plate and they get slowed down, quickly changing the electrons into x rays.

Question 20

Does the speed of water waves ever change?

Answer 20

No as the frequency increases the wavelength decreases.

Question 21

What is the relationship between the angle of incidence and the angle of reflection?

Answer 21

The angle of incidence is equal to the angle of reflection.

Question 22

Why do waves travel more slowly in shallower water?

Answer 22

As a wave enters a region of shallower water the wavelength is decreased, yet the frequency remains the same. In deeper water their wavelength increases.

Question 23

What is refraction?

Answer 23

When a change in speed causes a change in direction of travel at the boundary eg water waves bend towards the normal when travelling from deep to shallow water

Question 24

What is diffraction?

Answer 24

The spreading out of waves as they pass through a small gap.

Question 25

How do you define electromagnetic waves?

Answer 25

They all transfer energy and not matter. They all transverse, reflect, refract, diffract and travel at the same speed in a vacuum

Question 26

What are radio waves?

Answer 26

They are produced and transmitted by very rapidly alternating currents. They are received by aerials.

Question 27

Give the EM spectrum from low to high frequency

Answer 27

Radiowaves, microwaves, infrared, visible, ultraviolet, x-rays, gamma rays

Question 28

Uses of gamma radiation

Answer 28

Sterilizing surgical equipment: placed in a plastic bag (sealed to protect them from bacteria) and exposed to gamma rays. They pass through and kill living tissue such as viruses and bacteria. They kill bacteria in food by breaking chemical bonds
Investigating structures like jet engines which would obstruct x rays

Question 29

Uses of microwaves

Answer 29

Microwaves cook food containing water because the frequency of the microwaves coincide with natural frequencies of movement of the water molecules so they become agitated.
Satellite transmissions

Question 30

What are gamma rays?

Answer 30

Have the highest frequency of all waves.
Can detect through a Geiger mueller tube.
Takes several cm of lead to stop them. High doses kill living cells and lower doses cause mutation of cells or cancerous growths.

Question 31

Range of sound of human hearing?

Answer 31

20Hz - 20,000Hz

Question 32

Infrared uses

Answer 32

Night vision equipmeny 
Astronomy
Security systems
Heaters - hotter the object, the brighter it appears. 
Also used in toasters and grills.

Question 33

What are the risks of UV?

Answer 33

Damage to surface cells (can lead to skin cancer) and blindless

Question 34

What is ultrasound?

Answer 34

Sound that has a frequency about the range of human hearing (about 20kHz)

Question 35

What is ultrasound used for?

Answer 35

Pre natal scanning and sonar.

Question 37

What happens when a ray enters a new medium face on?

Answer 37

It may change speed but it won’t be refracted, it will continue in the same direction.

Question 38

Uses of visible light?

Answer 38

Optical fibres or photography

Question 39

What are the risks of infrared?

Answer 39

Skin burns

Question 40

What are the risks of microwaves?

Answer 40

Internal heating of body tissue

Question 41

What are the risks of gamma radiation?

Answer 41

Can cause cells to mutate and cause cancer

Question 42

What are sound waves?

Answer 42

Longitudinal waves which can be reflected, refracted and diffracted

Question 43

How would you measure the speed of sound in air?

Answer 43

1) Ask a friend to make a noise by banging two pieces of wood together as a clear visual signal.
2) If you stand 100m away, you can use a stopwatch to find the time form when you can see the two pieces of wood bang together and when you can hear the sound.
3) Repeat the experiment three times to obtain three different times and calculate an average.
4) Use the average time to calculate the average speed of sound in air by dividing the distance (100m) by the time. However, reaction times could be a problem
Control variables: need still air, and need to check/reset stopwatch zero reading before experiment

Question 44

How can you measure the speed of sound in air using echoes?

Answer 44

This is more accurate than wooden blocks
1) Stand 50m away from a large, blank wall and clap or bang two pieces of wood together and listen for the echo
2) Set up a rhythm of claps so that the echo comes exactly between two claps
3) Ask a friend to time 20 claps - during this time the sound has travelled 2000m (to the wall and back 20 times)
4) Repeat the experiment to get an average time and to make the experiment more reliable
5) You can divide the distance (2000m) by the average time
Control variables: need still air, need to check/reset stopwatch zero reading before experiment

Question 45

What property of electromagnetic waves makes then good for communication?

Answer 45

They can travel long distances and travel fast