15. P12 P13 Waves and EM Waves (Physics)

Question 1

What is the law of reflection?

Answer 1

Angle of incidence(i) = Angle of reflection(r)

Question 2

What is a transverse wave?

Answer 2

The particle oscillations are perpendicular to the direction of the energy.

Question 3

Give examples of transverse waves.

Answer 3

light, water, radio, microwave, infrared, UV, X-rays, Gamma

Question 4

What is a longitudinal wave?

Answer 4

The particle oscillations are parallel to the direction of the energy.

Question 5

Give an example of a longitudinal wave.

Answer 5

Sound

Question 6

What is a wave?

Answer 6

A wave transfers energy and information from one place to another.

Question 7

Define Wavelength

Answer 7

The Wavelength is the length of one complete wave. (the distance between two corresponding points on a wave)

Question 8

Units of wavelength?

Answer 8

Metres (although can be measured in mm, cm or km)

Question 9

Define Amplitude

Answer 9

The amplitude is the maximum disturbance caused by a wave from its rest position. (centre line of wave up to the peak or down to the trough)

Question 10

Define frequency

Answer 10

The frequency is the number of waves passing a point every second.

Question 11

Units of frequency?

Answer 11

Hertz (or Hz - must be capital H)

Question 12

Define period (T)

Answer 12

The period is the time it takes for one complete wave to pass a point

Question 13

Units of time period (T) of a wave?

Answer 13

seconds, s

Question 14

Equation to calculate wave speed?

Answer 14

wavespeed = frequency x wavelength (v = f x ?) (? - lambda = wavelength)

Question 15

Equation to calculate time period of a wave from the frequency?

Answer 15

T = 1 / f

Question 16

In a longitudinal wave, the name given to areas where the particles are close together?

Answer 16

Compression

Question 17

In a longitudinal wave, the name given to areas where the particles are spread out?

Answer 17

Rarefaction

Question 18

What is refraction of waves?

Answer 18

The change in the direction of travel when a wave crosses a boundary between one medium to another due to the wave changing speed.

Question 19

Water waves refract when what causes the speed of the wave to change?

Answer 19

Depth of the water

Question 20

Light waves refract when what causes the speed of the wave to change?

Answer 20

Moves from one material to another of a different optical density.

Question 21

The line on a ray diagram that all angles are measured from during reflection or refraction?

Answer 21

normal

Question 22

How do you draw a normal line at the point the light strikes the mirror?

Answer 22

Normal line is drawn perpendicular to the surface at the point the ray strikes the surface (using a dashed line)

Question 23

What happens when a wave enters a glass block from air (not along the normal)?(Wavespeed, Angle, Wavelength and Frequency)

Answer 23

Wavespeed slows down, ray bends towards the normal, wavelength shortens , but frequency stays the same.

Question 24

What happens when a wave leaves a glass block from air (not along the normal)?(Wavespeed, Angle, Wavelength and Frequency)

Answer 24

Wavespeed speeds up, ray bends away from the normal, wavelength increases, frequency DOES NOT change.

Question 25

What are the properties of an image formed with a plane mirror?

Answer 25

Upright, Virtual, Laterally inverted, same size.

Question 26

What is the difference between a virtual and real image?

Answer 26

A real image can be formed on a screen where as a virtual image can be seen but does not actually exist.

Question 27

What is the speed of sound waves in air?

Answer 27

330m/s although it does vary with temperature.

Question 28

How does a sound change when the amplitude decreases?

Answer 28

Quieter

Question 29

How does a sound change when the Wavelength increases?

Answer 29

Lower pitch

Question 30

How does a sound change when the frequency increases?

Answer 30

Higher Pitch

Question 31

What is meant by ultrasound?

Answer 31

Sound waves with a frequency above 20,000Hz

Question 32

State the human hearing range for someone with perfect hearing.

Answer 32

20 to 20,000Hz

Question 33

What is meant by infrasound?

Answer 33

Sound waves below a frequency of 20Hz

Question 34

What state of matter is sound waves fastest in and why?

Answer 34

Solids, Particles are tightly packed.

Question 35

Give some medical uses of Ultrasound.

Answer 35

Prenatal scanning, blood flow meters, break up kidney stones, images of organs

Question 36

Give some industrial uses of Ultrasound.

Answer 36

Fishing boats scanning for fish, sea floor mapping, detecting flaws/cracks in steel

Question 37

Describe how bats use ultrasound.

Answer 37

Echo-location. For navigation and catching prey. The look for the reflection of the ultrasounds they emit.

Question 38

What is the name given to the exact point an earthquake occurs?

Answer 38

epicenter

Question 39

What are Primary (P-Waves) ?

Answer 39

Longitudinal waves that push or pull on material that they pass through. These cause the initial tremors.

Question 40

What are Seconday (S-Waves) ?

Answer 40

Slower moving transverse waves which shake material from side to side. These cause tremors a few minutes after p-waves.

Question 41

What are Long (L-Waves) ?

Answer 41

These travel the slowest, and only can travel through the Earth's solid crust, causing violent movements up, down, backwards and forwards.

Question 42

State the four sections which make up the earth's structure.

Answer 42

Crust, Mantle, Outer core and Inner core

Question 43

Describe the differences between p-waves and s-waves.

Answer 43

S-waves are Transverse, slower and can't travel through liquids.

Question 44

Why can the s-waves not travel through the core of the earth?

Answer 44

Outer core is liquid, and s-waves can not pass through liquids.

Question 45

Describe what is meant by a mechanical wave.

Answer 45

A wave that requires a medium in which to travel i.e. water or a spring etc

Question 46

Describe what is meant by an electromagnetic wave.

Answer 46

Transverse waves that transfer energy by setting up electric and magnetic fields. Can travel through a vacuum.

Question 47

What is meant by the crest or peak of a wave?

Answer 47

The highest part of a transverse wave

Question 48

What is meant by the trough of a wave?

Answer 48

The lowest part of a transverse wave

Question 49

List the Electromagnetic waves in order from long to short wavelength

Answer 49

Radio, Microwave, Infrared, Visible, UV, X-ray and Gamma

Question 50

List the Electromagnetic waves in order from high to low frequency

Answer 50

Gamma, X-ray, UV, Visible, IR, Microwave, Radio

Question 51

State how a radiowave can be produced?

Answer 51

Oscillation in electrical circuits (vibration of charged particle such as electron)

Question 52

State a use of radiowaves?

Answer 52

Communication, television and radio

Question 53

State two uses of microwaves?

Answer 53

Heat food, mobile phones, Satelite tv, GPS

Question 54

State two uses of infrared?

Answer 54

heater, toaster, oven, treatment of muscle injuries, remote controls, infrared cameras

Question 55

State two uses of UV light?

Answer 55

Check for forged bank notes, sunbeds, investigating crime scenes, energy efficient lightbulbs.

Question 56

State two uses of X-rays?

Answer 56

airport security, check for broken bones

Question 57

State two uses of Gamma radiation?

Answer 57

Radiotherapy, sterilising surgical equipment, medical tracers, industrial tracers

Question 58

What are the two similarities of all electromagnetic waves?

Answer 58

All transverse, travel at the same speed in vacuum or air, transfer energy

Question 59

State the colours which make up visible light?

Answer 59

Red,Orange, Yellow, Green, Blue, Indigo and Violet.

Question 60

State a danger of UV light?

Answer 60

Ultraviolet waves can cause skin to age prematurely and increase the risk of skin cancer.

Question 61

State which types of EM waves are ionising radiation?

Answer 61

UV, X-ray and Gamma

Question 62

State what the effect on human tissue when they absorb Radio, Microwave, IR or visible?

Answer 62

Heating

Question 63

State what effect ionising radiation can have on human cells?

Answer 63

Can cause the mutation of genes and cancer.

Question 64

What two things do the effects of ionising radiation have on human body tissue depend on?

Answer 64

1) type of radiation and 2) the size of the dose.

Question 65

Radiation dose is measured in Sieverts, what is it a measure of?

Answer 65

It is the measure of the risk of harm resulting from an exposure of the body to the radiation.

Question 66

How many millisieverts are present in 5 sieverts of radiation dose?

Answer 66

5000millisieverts = 5 sieverts

Question 67

Which type of EM radiation can be used by fibre optic cables?

Answer 67

IR and visible light

Question 68

How are gamma rays generated?

Answer 68

Gamma rays are generated from changes within the nucleus of atoms.