3 Waves, Sound and EM Spectrum

Question 1

An ambulance is producing sound represented by wave 2

Which wave would represent the sound an observer would hear as the ambulance approached them?

Answer 1

Wave 3.

frequency increases and wavelength decreases as the ambulance approaches the observer.

Question 2

What is the use of UV radiation?

Answer 2

flourescent lamps

used to detect conterfeit money

Question 3

Give three properties (features) common to all EM waves

Answer 3

all travel at the same speed in a vaccum (3 x 10⁸m/s)

all transverse waves

all travel through a vacuum

Question 4

Which wave has the largest wavelength?

Answer 4

wave 1

largest distance between adjacent crests

Question 5

How can you make a transverse wave with a slinky?

Answer 5

Move your hand in a side to side movement

Question 6

Equation:

Wave speed v =

Answer 6

wave speed = wavelength x frequency

Question 7

Label the compressions, rarefactions and wavelength on the longitudinal wave below

Answer 7

Question 8

What is 204 nm in m?

Answer 8

n stands for nano (x10^-9)

204 x 10^-9 m

Question 9

What is the Doppler effect?

Answer 9

When there is a change in frequency of a wave if the source is moving towards or away from an observer.

Question 10

How can you make a longitudinal wave with a slinky?

Answer 10

move your hand in a forwards and backwards movement

Question 11

An ambulance is producing sound represented by wave 2

Which wave would represent the sound an observer would hear as the ambulance travelled away from them?

Answer 11

Wave 1.

The frequency of the sound would decrease and wavelength increase as the ambulance moves away from the observer.

Question 12

Fred noticed that 10 waves passed a point in 5 seconds. What is the frequency of the wave?

Answer 12

frequency = 10 waves/ 5 s

= 2 Hz

Question 13

What is 700 µm (micrometres) in metres?

Answer 13

µ = x 10^-6

700µm = 700 x 10^-6 m

Question 14

What is a wavefront?

Answer 14

A wavefront connects all points on a wave which are moving in time

Question 15

Which wave has the largest amplitude?

Answer 15

wave 2

It has the largest displacement from the equilibrium

Question 16

What is the unit for time period?

Answer 16

seconds or s

Question 17

What is the unit for amplitude?

Answer 17

metres (m)

Question 18

Match the following terms with their definition

Answer 18

frequency- the number of waves going past in one second

wavelength- the length of one repeat of the wave pattern

wave speed- how far a wave travels in one second

Question 19

Why are UV waves dangerous?

Answer 19

cause blindness

damage surface skin cells and cause skin cancer

Question 20

What is the use of microwaves?

Answer 20

cook food

mobile phones

satellites to send signals to satellite dishes

Question 21

What is a transverse wave?

Answer 21

Where the oscillation is 90° to the direction of wave travel

Question 22

What are the uses of infrared radiation (IR)

Answer 22

heaters

night vision

emitted by tv controllers to control t.v.

Question 23

What is the use of X-rays?

Answer 23

Used to detect breaks in bones

look inside materials for breaks eg wings of planes

Question 24

List the EM spectrum in order of increasing frequency

Answer 24

Radio

Microwave

IR

Visible

UV

X-ray

Gamma

Question 25

What is 13 kHz in Hz?

Answer 25

kilo k = x 10³ 13kHz = 13 x 10³ Hz

Question 26

What is the relationship between time period and frequency?

Answer 26

frequency = 1 / time period

Question 27

List the EM spectrum in order of decreasing wavelength

Answer 27

Radio Microwave IR Visible UV X-ray Gamma

Question 28

How is gamma radiation dangerous?

Answer 28

It can cause mutations in cells- cancer

Question 29

How are X-rays dangerous?

Answer 29

They can cause mutations of cells- cancer

Question 30

Label the wavelength, amplitude, crest and trough of the transverse wave below

Answer 30

Question 31

How is infrared dangerous?

Answer 31

It can cause skin burns if too hot

Question 32

What is a longitudinal wave?

Answer 32

oscillations are parallel to the direction of travel.

Question 33

Give three examples of a longitudinal wave

Answer 33

sound shock wave P wave

Question 34

What are the uses of radio waves?

Answer 34

broadcasting radio and tv signals radar walkie talkie signals

Question 35

What are the uses of gamma radiation?

Answer 35

Used to kill cancer tumours used to sterilise medical equipment and food

Question 36

What is 100 MHz in Hz?

Answer 36

mega M = x 10⁶ 100MHz = 100 x 10⁶ Hz

Question 37

What is the unit for wavelength?

Answer 37

metre or m

Question 38

Give three examples of a transverse wave

Answer 38

water wave any EM wave S wave

Question 39

Which wave has the highest frequency?

Answer 39

wave 3 ## Footnote *it has more waves per second*

Question 40

How are all the EM radiation different?

Answer 40

They have.... different wavelengths different frequencies therefore they have different uses and dangers

Question 41

What is the unit for wavespeed?

Answer 41

metre per second or m/s

Question 42

What is the use of visible light?

Answer 42

photography fibre optics

Question 43

What is the unit for frequency?

Answer 43

Hertz or Hz

Question 44

How is sound created?

Answer 44

sound is created by vibrations

Question 45

List some properties of sound

Answer 45

1. it is a longitudinal wave 2. it is created by a vibration 3. it cannot travel through a vacuum

Question 46

Does increasing temperature increase the speed of sound in air? Why?

Answer 46

No As temperature of air increases, speed of sound decreases. Particles in warm air are more spread out and collisions between particles are more difficult

Question 47

Sound is a series of compressions and rarefactions. How does the speed of sound compare in a solid, liquid and gas? Explain

Answer 47

Sound travel faster through a solid than a liquid and gas. Sound is a vibration which is transferred from particle to particle via collisions. Solid particles are closer together and have stronger forces between them- vibrations are passes between particles more quickly

Question 48

How can speed of sound **through air** be measured in a laboratory?

Answer 48

* connect **two microphones** to a **microsecond timer** * place the two microphones **2.00 metres** apart using two metre rules * place **padding under each microphone** to prevent sound travelling through the table * create a **sharp sound** behind the first microphone * **record the time** it takes for the sound to travel from microphone 1 to microphone 2 * **repeat five times** and **calculate the mean** time * calculate the speed of sound through air by s = 2.00 m / mean time

Question 49

Bats locate their prey by echosounding. They use pulses of ultrasound and listen for the echo with their large ears. If the time between the pulse and echo is small, the insect is closer to the bat. Name another animal which uses echo sounding.

Answer 49

dolphins

Question 50

When calculating the distance in an echosounding question, what is the most common error?

Answer 50

The distance calculated from the speed of sound and time for echo must be divided by two!

Question 51

What is the human hearing range?

Answer 51

20 - 20 000 Hz

Question 52

What is ultrasound?

Answer 52

Any sound over 20 000 Hz

Question 53

Ultrasound is used to image babies in the womb. An image is formed on the screen if reflections are received from the different surfaces (layers) of the baby. How does the time for the reflection relate to the distance to the surface?

Answer 53

The further the surface is from the ultrasound transmitter/receiver, the longer it takes for the echo to return.

Question 54

The distance to a storm can be calculated using the lightning seen and the thunder heard. What assumption is made in this calculation?

Answer 54

Question 55

If **low frequency** is **low pitch** sound. What is high frequency sound?

Answer 55

High frequency = high pitch

Question 56

What type of wave is sound?

Answer 56

Longitudinal vibrations are parallel to direction of wave travel

Question 57

What do waves do?

Answer 57

transfer energy and information without transferring matter

Question 58

Dangers of microwaves?

Answer 58

internal heating of body tissues

Question 59

If the loudness of sound increases, what also increases?

Answer 59

amplitude