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Physics > Electromagnetic waves > Flashcards

Electromagnetic waves Flashcards

1
Q

What his the Order of radiation from long to short

A

Radioactive
Microwave
Infrared
Visible
Ultra violet
X-ray
Gamma ray

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2
Q

What is the speed of light

A

3 x (10 x 8)

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3
Q

Which radiation has the highest energy and why

A

Gamma rays because it is highly penetrable and ionising

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4
Q

What is ionising wave

A

It can remove an electron from an atom

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5
Q

What does it mean if a radiation has high energy

A

It is easy for the waves to penetrate matter rather than being absorbed
However the higher the energy the more damage caused by radiation

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6
Q

What is absorbtion

A

Transfer of energy from the wave to the medium (light and a curtain-medium)

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7
Q

What is white light

A

Visible light from the sun or a regular lamp

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8
Q

What is an endoscope

A

It is a medical equipment that contains 2 bundles of fibre. One set of fibres transmits light into a body cavity and the other is used to return an image inside the cavity

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9
Q

What are radio waves used for

A

To carry to and mobile signals
Bluetooth enables devices to use low powered radio waves to communicate and transfer wireless signal

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10
Q

What is the ionosphere

A

The part of the atmosphere that is ionised by solar radiation

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11
Q

Why are radio waves reflected by the ionosphere

A

Because it can not penetrate the ionosphere but microwaves can

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12
Q

How do microwaves heat food

A

They penetrate the food and are absorbed by the water and fat molecules which cause them to vibrate and emit IR radiation thus heating up

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13
Q

What are example of where infrared radiaton

A

Optical fibres
Communication systems
Infrared cameras
Infrared scanners

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14
Q

How is infrared radiation used for communication

A

Equipment transmits signals through sending and receiving impulses of IR radiation

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15
Q

What can infrared scanners be used for

A

To detect IR emitted from hotspots in the bidy

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16
Q

Give an example of communication with infrared and microwave radiation

A

IR - remote control
Micro- cell phones

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17
Q

State 2 properties that are the same for microwaves and IR

A

they both travel at the same speed
They are transverse waves

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18
Q

What is the range of wavelengths od electromagnetic waves

A

10 to the power of - 15
To 10 to the power of 4

19
Q

What is a black body radiation

A

They are objects that are completely black and are perfect absorbers and emitters of radiation, none is reflected or transmitted

20
Q

What type of waves are electromagnetic waves

A

Transverse

21
Q

How are electromagnetic waves grouped in the electromagnetic spectrum

A

Terms of the frequency and wavelength

22
Q

How do radio waves generate electric currents

A

They transfer energy to the kinetic energy source of electrons in radio receivers

23
Q

What are electromagnetic waves vibrations off

A

Electric and magnetic field

24
Q

Why can electromagnetic waves travel in a vacuum

A

Because they are vibrations of electric and magnetic field not particles

25
Q

How do you draw ray diagrams

A

Start by drawing the boundary line between your two materials (horizontal)
Then draw the normal which is an imaginary line that is perpendicular to where the the incoming wave hits the boundary.
Draw an Incident ray that meets the normal at the boundary (where the wave hits the boundary.
The angle between the incident ray and the normal is the angle of incidence.
Then draw the refracted ray opposite to the incident ray
The angle of refraction is between the refracted ray and the normal.

26
Q

How are electromagnetic waves produce

A

Alternating currents made up of oscillating charges and as the charges oscillate they produce oscillating electric and magnetic field

27
Q

What happens to the light as it passes from the surroundings to the glasses

A

Turn off the light is reflected back and some of the light transmit through

28
Q

Explain how a light rays speed and direction change when passing through glass into a vacuum

A

It will speed up and bend away from the normal

29
Q

What happens when radio waves are absorbed

A

They may create an alternating current with the same frequency is the radio wave itself therefore they can induce oscillations in electrical circuits

30
Q

How are electromagnetic waves generated

A

By changes in atoms and the nuclei of atoms

31
Q

What does the effect of hazardous raise on human body tissue depend on

A

The dose And the type of electromagnetic wave

32
Q

What is radiation dose

A

The measure of the risk of harm resulting from an exposure of the body to the radiation

33
Q

How many milli sievert are in one Sievert

A

1000

34
Q

What is a Leslie cube

A

A hollow water type metal cube made of aluminium with four vertical faces that have different surfaces

35
Q

Describe an experiment with infrared radiation

A

Hey some empty Leslie cube on heatproof mat
Then boil water in a castle and feel the Leslie here with the water
Wait for a few minutes for the kids to warm up then hold a thermometer against each of the faces all four should have the same temperature
Then hold an infrared detector at a distance away from one of the faces and record the IR radiation
Then repeat this for each of the faces with the infrared radiation detector at the same distance.

36
Q

Describe the result of the Leslie cube experiment

A

There should be more infrared radiation from the black surface than the white one and more from the mat surfaces from the shiny ones

37
Q

What happens when an object absorbs microwaves

A

It will become hot

38
Q

What should scientist do to find out whether phones affect health

A

Compare the health of non mobile users
With mobile users

39
Q

Infrared radiation is passed through glass. 70 per cent is transmitted and 5 percent is reflect how much is absorbed

A

25 percent

40
Q

What happens when a metal Ariel absorbs radio waves

A

It creates an alternating current with the same frequancy as the wave causing it to heat up

41
Q

Why can we assume that visible light and microwaves travel at the same speed

A

All EM waves travel at the same speed in a vacuum

42
Q

Which object has the greatest rate of energy transfer in order from best to least and why:
Start temp. Finish temp
A. 70. 5
B. 80. 0
C. 90. 30

A

B A C
Biggest temp diff

43
Q

Which can with boiling water will get to room temp faster
Dark Matt
Dark shiny
Light Matt
Light shiny

A

Dark Matt because it is the best absorber

Physics (12 decks)

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