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Extension Flashcards

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1
Q

What form of diagnosis equipment uses visible light?

A

Endoscopes

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2
Q

In what diagnosis equipment are X-Ray’s used?

A

X-Ray photography and CAT scanners

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3
Q

In what diagnosis equipment are gamma rays used?

A

PET scanners

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4
Q

In what diagnosis equipment is ultrasound used?

A

Ultrasound scanners

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5
Q

What are lasers used for in terms of illness/health?

A

Laser eye surgery

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6
Q

What does absorption of ultrasound help to treat?

A

Swollen tissues

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7
Q

What two things affect the intensity of radiation?

A

Distance from the source and the medium

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8
Q

What is intensity measured in?

A

Watts per metres squared

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9
Q

What is the role of the retina?

A

It converts the image into electrical impulses which are carried from the optic nerve to the brain

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10
Q

What part of the eye controls the amount of light that reaches the retina?

A

The iris

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11
Q

At close distance, does the lense contract or relax?

A

It contracts to a fatter shape

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12
Q

At a further distance, is the ciliary muscle relaxed or contracted?

A

The muscle is relaxed and pulls the lens into a thinner shape

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13
Q

What is your far point?

A

How far you can see (infinity)

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14
Q

What is your near point?

A

The closest you can see an un-blurred image

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15
Q

What does it mean to have short sight?

A

It means close objects are clear and far away objects are blurred

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16
Q

What causes short sightedness?

A

Eyeball being too long or the cornea being curved too sharply

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17
Q

Where is the image focused in people with short sight?

A

In front of the retina

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18
Q

What does it mean to be long sighted?

A

Distant objects are clear but near objects are blurred

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19
Q

What are the causes of long sightedness?

A

Eyeball being too short or lens not being thick enough or not curved enough

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20
Q

Where does the image of someone with long sight focus?

A

Behind the retina

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21
Q

What type of lens do short sight people wear?

A

Diverging

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22
Q

What kind of lens should someone with long sight wear?

A

Converging

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23
Q

How does laser correction work?

A

A laser beam reshape stone front of the cornea

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24
Q

What is the power of a lens measured in?

A

Dioptres

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25
Q

What is the equation for a measurement in Dioptres?

A

1/focal length (metres)

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26
Q

What is the lens equation?

A

1/f = 1/u + 1/v

F - focal length
U - object distance
V - image distance

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27
Q

What is a real image?

A

An image that can be seen on a screen, has a positive image distance

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28
Q

What is a am virtual image?

A

An image that can’t be projected (has a negative image distance)

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29
Q

What does the law of reflection state?

A

Angle of incidence = angle of reflection

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30
Q

How does light refract when it speeds up?

A

It refracts away from the normal

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31
Q

How does light refract when it slows down?

A

It refracts towards the normal

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32
Q

What is Snell’s law?

A

Sin I / sin r = nr / ni

N = refractive index

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33
Q

When the angle of incidence is bigger than the critical angle, what happens?

A

Total internal reflection

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34
Q

What happens when the angle of incidence is less than the critical angle?

A

Refraction and reflection

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35
Q

What happens when the able of incidence is equal to the critical angle?

A

The light will travel along the boundary

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36
Q

How do automatic windscreen wipers use total Intel reflection?

A

When it is sunny, the infrared source will be totally internally reflected however when it rains some of the source will refract through the water, the sensors detect the decrease in the infrared which then turns the wipers on

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37
Q

What is the equation for calculating the critical angle?

A

Sin C / Sin R = Nr / Ni

C - critical angle

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38
Q

How do optical fibres work?

A

No matter how the fibre is twisted, the light ray will be repeatedly reflected back into the fibre. This is used for telephones, TV and other communications

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39
Q

How do endoscopes allow doctors to view inside the persons digestive system?

A

By using optical fibres that ensure the rod is flexible so the doctor can view inside the person

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40
Q

What is ultrasound used for? (2)

A

Locating and breaking up kidney stones and also by physiotherapists to treat injured muscles

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41
Q

Why are x-Ray’s made in an evacuated tube?

A

So that the electrons do not collide with other particles as they cross the tube

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42
Q

Through what process does the cathode wire filament emit electrons as an electron gun?

A

Thermionic emission

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43
Q

What must there be between the anode and cathode for the electrons to accelerate towards the anode?

A

A large potential difference

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44
Q

What happens when the electrons collide with the anode?

A

Their kinetic energy transfers to thermal energy and some is transformed into X-rays

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45
Q

Why does the anode spin (in an X-ray machine)?

A

To prevent wear and to prevent overheating

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46
Q

Describe how an X-ray photo shows denser areas?

A

The dark areas on the photo is where more X-rays have been detected and less absorbed and light areas are dense areas where X-rays were absorbed

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47
Q

How do CAT scans work?

A

An X-ray source is moved around the patient in a circle and a detector is on the opposite side of the source, they are used to create cross sectional views of the body to create a 3D image

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48
Q

What do unusual areas of brightness or darkness show in a CAT scan?

A

They can indicate dead tissue or tumours

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49
Q

How do fluoroscopes work?

A

They show the patients working organs as the person is places between the X-ray source and the detector which is attached to a digital video camera

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50
Q

Why are CAT scans and fluoroscopes beneficial?

A

They are painless and non invasive and eliminate the need for biopsy

51
Q

What are the drawbacks of fluoroscopes and CAT scans?

A

They can give a dose of radiation equivalent to 10 years of background radiation which increases risk of cancer

52
Q

Why are X-rays fired from several directions when treating cancer?

A

So that only the tumour receives the high dose and surrounding tissue damage is kept to a minimum

53
Q

What is an action potential?

A

An electrical signal sent to each muscle in the heart which tells it when to contract

54
Q

Describe the movement of the muscles in the heart when it beats

A

First muscles in the atria contract, followed by the ventricle walls and finally the contraction will spread up from the base of the ventricles

55
Q

What does an electrocardiogram show?

A

It is a picture of the heart electrical signals

56
Q

Once the time period of a heartbeat is worked out, how is frequency worked out?

A

1 / Time period (s)

57
Q

How is bpm found from the frequency?

A

By multiplying the frequency by 60

58
Q

Name another way that pulse rate can be found (not from an ECG)

A

Pulse oximetry

59
Q

What do the two LEDs in the pulse oximeter emit?

A

One emits red light and one emits infrared

60
Q

Describe how the light passes through oxygenated blood in a pulse oximeter

A

Some red light passes through and less infrared passes through

61
Q

What does a pacemaker do?

A

It detects action potentials, snip kitties them and transmits them to other parts of the heart so that the chambers of the heart contract correctly

62
Q

Describe what happens in B- decay

A

A neutron becomes a proton plus an electron

63
Q

How does B- decay affect the atomic number and mass number?

A

It increases the atomic number by one and leaves the mass number unaffected

64
Q

Describe what happens in B+ decay

A

A proton becomes a neutron plus a positron

65
Q

How does B+ decay affect the atomic number and mass number?

A

Decreases the atomic number by one and leaves mass number unaffected

66
Q

Name 2 things that beta radiation is used for?

A

Paper thickness and checking medicine bottles are filled e correct amount

67
Q

Why are alpha particles not very penetrating?

A

Because they’re so massive and therefore lose energy very quickly

68
Q

How does alpha decay affect the mass number and atomic number?

A

Decreases atomic number by 2 and decreases mass number by 4

69
Q

Why does gamma radiation make the nucleus more stable?

A

Because it is losing energy

70
Q

Why aren’t neutrons directly ionising?

A

Because they have no charge

71
Q

How penetrating are neutrons?

A

They are as penetrating as gamma rays

72
Q

How is alpha represented in a nuclear equation?

A

As helium 4-2

73
Q

How is an electron shown in a nuclear equation?

A

0–1 e

74
Q

How is a positron shown in a nuclear equation?

A

0-+1 e

75
Q

How is a gamma ray shown in a nuclear equation?

A

0-0 Y

76
Q

What does the stability curve show?

A

It shows isotopes with the same number protons as neutrons (these are stable)

77
Q

Why does the stability curve on,y go up to Z = 82?

A

Because all isotopes above is are unstable

78
Q

What kind of decay do isotopes above the stability curve undergo?

A

B- decay

79
Q

What kind of decay to isotopes below the curve undergo?

A

B+ decay

80
Q

Isotopes above z=82, usually undergo what decay?

A

Alpha

81
Q

How many quarks does a sub-atomic particle contain? (Protons/neutrons)

A

3

82
Q

What is the charge of an up quark?

A

2/3

83
Q

What is the charge of a down quark?

A

-1/3

84
Q

Describe the arrangement of quarks in a proton

A

Up-up-down

85
Q

Describe the arrangement of the quarks in a neutron

A

Down-up-down

86
Q

What happens in terms of quarks during B+ decay?

A

An up quark becomes a down quark

87
Q

What happens in terms of quarks during B- decay?

A

A down quark changes to an up quark

88
Q

How can radiation exposure cause cancer?

A

Because it can cause mutations in DNA

89
Q

What do beta burns look like?

A

Sun burn

90
Q

What precautions are taken by those working with radiation on a daily basis?

A

Increasing distance from source, shielding, containment of source and minimising time spent in the presence of sources

91
Q

What is radiotherapy used for?

A

Treatment of cancers

92
Q

Describe palliative care

A

Its care that will not cure the patient but will keep them comfortable

93
Q

What kind of radiation is used in internal radiotherapy?

A

A beta emitter such as iodine-131

94
Q

What radiation does external radiotherapy use?

A

A gamma source or high frequency X-Ray’s

95
Q

What do tracers do?

A

They are inserted into the the body and will concentrate in particular organs or diseased tissues or cancer tumours

96
Q

Why do tracers need to have a short half life?

A

So that other parts of the body are affected as little as possible

97
Q

What does the PET scan do in terms of cancer diagnosis?

A

The PET scan will locate the tracer

98
Q

Why is particle physics useful?

A

It helps scientists to understand sub-atomic particles as well as the smaller fundamental particles

99
Q

What is the LHC and what does it do?

A

It’s a particle accelerator which can accelerate two beams of protons or ions to allow them to collide head on

100
Q

Why is collaborative, international research beneficial?

A

It brings together expertise from all over the world and shares cost of experiments

101
Q

What is the centripetal force?

A

A force that acts inwards along the radius and allows and object to keep swinging in a circle

102
Q

Why does the object travel in a straight line once it has been released? (Circular motion)

A

Because there is no longer a centripetal force acting upon it

103
Q

What is a cyclotron?

A

A particle accelerator in which moving charged particles are bent into circular or spiral paths

104
Q

Why is a magnetic field at a right angle to the particles motion used?

A

It produces the centripetal force that is required

105
Q

What accelerates the charged particles in a cyclotron?

A

A voltage placed across the gap between the two d shaped magnets is used to accelerate the particles

106
Q

What happens if a high energy proton collides with a stab,e element?

A

A radioactive isotope is produced

107
Q

What are small cyclotrons used in hospitals for?

A

To produce the short lived isotopes needed in PET scanners

108
Q

What is the difference between an elastic and inelastic collision?

A

Momentum is conserved in both however kinetic energy is not conserved in an inelastic collision but is conserved in an elastic collision

109
Q

What is anti-matter?

A

Matter that has particles of the same mass and properties but opposite charge

110
Q

What happens when an electron and positron collide?

A

Annihilation occurs and two gamma rays are produced moving in opposite directions

111
Q

What is mass-energy equivalence?

A

It means that the masses of the annihilated positron and electron are converted into an equivalent amount of energy

112
Q

What is the energy equivalent of an electron?

A

8 x 10^-14 J

113
Q

What is the amount of energy released in positron-electron annihilation?

A

1.6 x 10^-13 J

114
Q

How is annihilation used in PET scanners?

A

A tracer that emits positrons is injected into the body which accumulates in certain areas. The positron then comes into contact with an electron and two gamma rays are produced which are picked up by the surrounding detectors so an image can be formed

115
Q

What is absolute zero?

A

-273 degrees - the temperature at which the pressure of a gas would be at 0 and the particles wouldn’t be moving

116
Q

What is the kelvin temperature scale?

A

Temperature relative to absolute zero - (0 K)

117
Q

How do you convert kelvin to Celsius?

A

From kelvin to Celsius: subtract 273

From Celsius to kelvin: add 273

118
Q

Why do gases need to be kept at a pressure above atmospheric pressure?

A

So that they can contain a bigger volume of gases

119
Q

If the volume of a gas increases at a constant temperature, what happens in regards to pressure?

A

Pressure decreases

120
Q

What is the equation that links volume and pressure?

A

V1P1 = V2P2

V = volumes in m^3
P = pressures in Pa
121
Q

If temperature of a gas is increased at a constant pressure, what happens in regards to volume?

A

Volume increases

122
Q

What is the equation that links temperature and volume?

A

V1 = V2T1 / T2

123
Q

When calculating volume, pressures and temperature in terms of gas, what temperature scale do we use?

A

Kelvin

124
Q

What is the equation that links pressure, volume and temperature?

A

P1V1 / T1 = P2V2 / T2

Physics (2 decks)

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