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N5 Physics > Radiation And Waves > Flashcards

Radiation And Waves Flashcards

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1
Q

What is ionisation?

A

It is the addition or removal of an electron to create an ion

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2
Q

What happens if you:

(a) Lose an election?
(b) Gain an electron?

A

(a) Creates a positive ion

(b) Creates a negative ion

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3
Q

How are electrons lost?

A

Ionising radiation comes close to / collides with the atom and forces the electron away

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4
Q

Name the three types of ionising radiation

A

Alpha - helium nucleus
Beta - fast moving electron
Gamma - high energy electromagnetic wave

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5
Q

What is the mass and charge of the three radiations?

A

Alpha - large mass, strong positive charge

Beta - very small mass, negative charge

Gamma - no mass, no charge

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6
Q

What is penetrating power?

A

Radiation has a different ability to penetrate materials. The material is said to have absorbed the radiation.

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7
Q

Rate the radiations from least penetrating to most

A

Alpha - thickness of skin

Beta - few millimetres of aluminium

Gamma - several centimètres of lead

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8
Q

What is radioactive decay?

A

It’s when the nuclei of some atoms are unstable, they naturally release off ionising radiation which allows the nucleus to become stable

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9
Q

What natural resources produce background radiation?

A

The ground, building materials, food and cosmic rays from space

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10
Q

Which radioactive gas do rocks produce?

A

Radon

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11
Q

Give examples of artificial radiation

A

Radioactive waste from nuclear power stations, radioactive fallout from nuclear weapons testing and medical x-rays

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12
Q

What percentage of average background radiation does does artificial sources account for?

A

15%

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13
Q

How does a Geiger miller tube work?

A

When radiation enters it produces ions in the gas. The ions produce a current which produces a voltage pulse. These pulses are counted and displayed on a GM tube.

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14
Q

How do you get a proper indication of how radioactive a source is?

A

Measure the number of ionisations per second or the count rate

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15
Q

What is the count rate usually called and how is it given?

A

The activity and it’s given by the number of counts or ionisations per second

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16
Q

What is the activity of a radioactive source and how is it measured?

A

It is the number of decays per second and it’s measured in becquerels

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17
Q

What do the letters stand for and their units in the formula for the activity?

A = N/t

A

A - activity of source in becquerels (Bq)

N - number of decays

t - time in seconds (s)

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18
Q

What is background radiation?

A

Radiation from natural sources and man made sources that is around us all the time. Usually less than 1Bq

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19
Q

What is half life?

A

Half life is the time taken for the activity of a radioactive source to reduce by half

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20
Q

What is absorbed dose?

A

It is the energy absorbed per unit mass of the absorbing materials

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21
Q

Label the equation and state the units:

D = E/m

A

D - absorbed does in grays (Gy)

E - energy absorbed in joules (J)

m - mass of absorbing tissue (kg)

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22
Q

What is the radiation weighting factor?

A

It is the measure of the biological effect of different types of ionising radiation

23
Q

what are the weighing factors for the radiations below:

Alpha
Beta
Fast neutrons
Gamma
Slow neutrons
A 
20
1
10
1
3
24
Q

What is equivalent does?

A

It takes into account the type of radiation and the total energy
absorbed

25
Q

Label and state the units for the formula for equivalent dose below:

H =D x Wr

A

H - equivalent dose in sieverts (Sv)

D - absorbed dose in grays (Gy)

Wr - radiation weighing factor

26
Q

What does equivalent dose rate tell us?

A

The equivalent dose a person receives over a specified period of time

27
Q

Label and state the units of the formula below:

H = H/t

A

H - equivalent dose rate in sieverts per hour (Sv/hr)

H - equivalent dose in sieverts (Sv)

t - time (hr)

28
Q

Name a few examples of how someone can protect themselves from radiation

A 
Keeping distance
Using tongs
Storing sources in lead lined boxes
Labelling all radioactive sources
Wearing a film badge to monitor exposure
Wearing protective clothing
29
Q

What are the prefixes and multiplication factors of the symbols below:

M
k
m
G
u
n
A 
Mega 10x6
Kilo 10x3
Milli 10x-3
Giga 10x9
Micro 10x-6
Nano 10x-9
30
Q

What is the equation for half life?

A

Half life in days = number of days / number of half lives

31
Q

What do waves do and how?

A

They transfer energy from one point to another by vibrating particles up and down or back and forth

32
Q

What is the wavelength of a wave?

A

The length of one complete wave

33
Q

How do you calculate wavelength?

A

Wavelength = distance / number of waves

34
Q

What is the frequency of a wave and how is it measured?

A

It is how many waves pass a particular point in one second

It’s measured in hertz (Hz)

35
Q

What is the formula for frequency?

A

Frequency = number of waves / time

36
Q

The _____ of a wave is the time for one complete wave to pass a point in seconds

A

Period (T)

37
Q

What is the formula to calculate the period?

A

T = 1/f

38
Q

What is wave speed?

A

How far a wave travels in one second

39
Q

What is diffraction?

A

When a wave bends around an obstacle or spreads through a gap

40
Q

What type of wave diffracts more?

A

Longer waves

41
Q

How does gap size affect diffraction?

A

The smaller the gap the bigger the diffraction

42
Q

What is constructive diffraction?

A

When two waves that are in-phase meet (crest to crest, trough to trough) the amplitude doubles

43
Q

What is destructive diffraction?

A

When two waves out of phase meet (crest to trough, trough to crest) they cancel each other out

44
Q

What does the law of reflection state?

A

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

45
Q

What is refraction?

A

It is when light passes from one medium to another

46
Q

What happens to the speed of light when it enters a more dense material like glass?

A

It slows down then speeds up when it enters a less dense material like air

47
Q

Which direction does light bend towards the normal?

A

It bends towards the normal when it passes to dense material and bends away when passing to air

48
Q

Name the two lenses:

_
\ /
/ \

()

A

Concave (diverging)

Convex (converging)

49
Q

What do convex lenses do?

A

Converges (focuses) the parallel light beams on the focal point. (The light is more intense at the focal point)

50
Q

What do concave lenses do?

A

Causes parallel light beams to spread out (diverge)

51
Q

What is the electromagnetic spectrum?

A

The em spectrum is a family of waves that don’t require particles to travel

52
Q

If the em spectrum waves don’t require particles, where can they travel?

A

A vacuum eg. Space

53
Q

What speed do em waves travel?

A

The speed of light 3x10 8

54
Q

What is the order of the em spectrum?

A 
Radio
Microwave
Infrared
Visible
Ultraviolet 
X-ray
Gamma ray

N5 Physics (3 decks)

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