Extension Flashcards
(124 cards)
1
Q
What form of diagnosis equipment uses visible light?
A
Endoscopes
2
Q
In what diagnosis equipment are X-Ray’s used?
A
X-Ray photography and CAT scanners
3
Q
In what diagnosis equipment are gamma rays used?
A
PET scanners
4
Q
In what diagnosis equipment is ultrasound used?
A
Ultrasound scanners
5
Q
What are lasers used for in terms of illness/health?
A
Laser eye surgery
6
Q
What does absorption of ultrasound help to treat?
A
Swollen tissues
7
Q
What two things affect the intensity of radiation?
A
Distance from the source and the medium
8
Q
What is intensity measured in?
A
Watts per metres squared
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
10
Q
What part of the eye controls the amount of light that reaches the retina?
A
The iris
11
Q
At close distance, does the lense contract or relax?
A
It contracts to a fatter shape
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
13
Q
What is your far point?
A
How far you can see (infinity)
14
Q
What is your near point?
A
The closest you can see an un-blurred image
15
Q
What does it mean to have short sight?
A
It means close objects are clear and far away objects are blurred
16
Q
What causes short sightedness?
A
Eyeball being too long or the cornea being curved too sharply
17
Q
Where is the image focused in people with short sight?
A
In front of the retina
18
Q
What does it mean to be long sighted?
A
Distant objects are clear but near objects are blurred
19
Q
What are the causes of long sightedness?
A
Eyeball being too short or lens not being thick enough or not curved enough
20
Q
Where does the image of someone with long sight focus?
A
Behind the retina
21
Q
What type of lens do short sight people wear?
A
Diverging
22
Q
What kind of lens should someone with long sight wear?
A
Converging
23
Q
How does laser correction work?
A
A laser beam reshape stone front of the cornea
24
Q
What is the power of a lens measured in?
A
Dioptres
25
What is the equation for a measurement in Dioptres?
1/focal length (metres)
26
What is the lens equation?
1/f = 1/u + 1/v
F - focal length
U - object distance
V - image distance
27
What is a real image?
An image that can be seen on a screen, has a positive image distance
28
What is a am virtual image?
An image that can't be projected (has a negative image distance)
29
What does the law of reflection state?
Angle of incidence = angle of reflection
30
How does light refract when it speeds up?
It refracts away from the normal
31
How does light refract when it slows down?
It refracts towards the normal
32
What is Snell's law?
Sin I / sin r = nr / ni
N = refractive index
33
When the angle of incidence is bigger than the critical angle, what happens?
Total internal reflection
34
What happens when the angle of incidence is less than the critical angle?
Refraction and reflection
35
What happens when the able of incidence is equal to the critical angle?
The light will travel along the boundary
36
How do automatic windscreen wipers use total Intel reflection?
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
37
What is the equation for calculating the critical angle?
Sin C / Sin R = Nr / Ni
C - critical angle
38
How do optical fibres work?
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
39
How do endoscopes allow doctors to view inside the persons digestive system?
By using optical fibres that ensure the rod is flexible so the doctor can view inside the person
40
What is ultrasound used for? (2)
Locating and breaking up kidney stones and also by physiotherapists to treat injured muscles
41
Why are x-Ray's made in an evacuated tube?
So that the electrons do not collide with other particles as they cross the tube
42
Through what process does the cathode wire filament emit electrons as an electron gun?
Thermionic emission
43
What must there be between the anode and cathode for the electrons to accelerate towards the anode?
A large potential difference
44
What happens when the electrons collide with the anode?
Their kinetic energy transfers to thermal energy and some is transformed into X-rays
45
Why does the anode spin (in an X-ray machine)?
To prevent wear and to prevent overheating
46
Describe how an X-ray photo shows denser areas?
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
47
How do CAT scans work?
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
48
What do unusual areas of brightness or darkness show in a CAT scan?
They can indicate dead tissue or tumours
49
How do fluoroscopes work?
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
50
Why are CAT scans and fluoroscopes beneficial?
They are painless and non invasive and eliminate the need for biopsy
51
What are the drawbacks of fluoroscopes and CAT scans?
They can give a dose of radiation equivalent to 10 years of background radiation which increases risk of cancer
52
Why are X-rays fired from several directions when treating cancer?
So that only the tumour receives the high dose and surrounding tissue damage is kept to a minimum
53
What is an action potential?
An electrical signal sent to each muscle in the heart which tells it when to contract
54
Describe the movement of the muscles in the heart when it beats
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
What does an electrocardiogram show?
It is a picture of the heart electrical signals
56
Once the time period of a heartbeat is worked out, how is frequency worked out?
1 / Time period (s)
57
How is bpm found from the frequency?
By multiplying the frequency by 60
58
Name another way that pulse rate can be found (not from an ECG)
Pulse oximetry
59
What do the two LEDs in the pulse oximeter emit?
One emits red light and one emits infrared
60
Describe how the light passes through oxygenated blood in a pulse oximeter
Some red light passes through and less infrared passes through
61
What does a pacemaker do?
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
Describe what happens in B- decay
A neutron becomes a proton plus an electron
63
How does B- decay affect the atomic number and mass number?
It increases the atomic number by one and leaves the mass number unaffected
64
Describe what happens in B+ decay
A proton becomes a neutron plus a positron
65
How does B+ decay affect the atomic number and mass number?
Decreases the atomic number by one and leaves mass number unaffected
66
Name 2 things that beta radiation is used for?
Paper thickness and checking medicine bottles are filled e correct amount
67
Why are alpha particles not very penetrating?
Because they're so massive and therefore lose energy very quickly
68
How does alpha decay affect the mass number and atomic number?
Decreases atomic number by 2 and decreases mass number by 4
69
Why does gamma radiation make the nucleus more stable?
Because it is losing energy
70
Why aren't neutrons directly ionising?
Because they have no charge
71
How penetrating are neutrons?
They are as penetrating as gamma rays
72
How is alpha represented in a nuclear equation?
As helium 4-2
73
How is an electron shown in a nuclear equation?
0--1 e
74
How is a positron shown in a nuclear equation?
0-+1 e
75
How is a gamma ray shown in a nuclear equation?
0-0 Y
76
What does the stability curve show?
It shows isotopes with the same number protons as neutrons (these are stable)
77
Why does the stability curve on,y go up to Z = 82?
Because all isotopes above is are unstable
78
What kind of decay do isotopes above the stability curve undergo?
B- decay
79
What kind of decay to isotopes below the curve undergo?
B+ decay
80
Isotopes above z=82, usually undergo what decay?
Alpha
81
How many quarks does a sub-atomic particle contain? (Protons/neutrons)
3
82
What is the charge of an up quark?
2/3
83
What is the charge of a down quark?
-1/3
84
Describe the arrangement of quarks in a proton
Up-up-down
85
Describe the arrangement of the quarks in a neutron
Down-up-down
86
What happens in terms of quarks during B+ decay?
An up quark becomes a down quark
87
What happens in terms of quarks during B- decay?
A down quark changes to an up quark
88
How can radiation exposure cause cancer?
Because it can cause mutations in DNA
89
What do beta burns look like?
Sun burn
90
What precautions are taken by those working with radiation on a daily basis?
Increasing distance from source, shielding, containment of source and minimising time spent in the presence of sources
91
What is radiotherapy used for?
Treatment of cancers
92
Describe palliative care
Its care that will not cure the patient but will keep them comfortable
93
What kind of radiation is used in internal radiotherapy?
A beta emitter such as iodine-131
94
What radiation does external radiotherapy use?
A gamma source or high frequency X-Ray's
95
What do tracers do?
They are inserted into the the body and will concentrate in particular organs or diseased tissues or cancer tumours
96
Why do tracers need to have a short half life?
So that other parts of the body are affected as little as possible
97
What does the PET scan do in terms of cancer diagnosis?
The PET scan will locate the tracer
98
Why is particle physics useful?
It helps scientists to understand sub-atomic particles as well as the smaller fundamental particles
99
What is the LHC and what does it do?
It's a particle accelerator which can accelerate two beams of protons or ions to allow them to collide head on
100
Why is collaborative, international research beneficial?
It brings together expertise from all over the world and shares cost of experiments
101
What is the centripetal force?
A force that acts inwards along the radius and allows and object to keep swinging in a circle
102
Why does the object travel in a straight line once it has been released? (Circular motion)
Because there is no longer a centripetal force acting upon it
103
What is a cyclotron?
A particle accelerator in which moving charged particles are bent into circular or spiral paths
104
Why is a magnetic field at a right angle to the particles motion used?
It produces the centripetal force that is required
105
What accelerates the charged particles in a cyclotron?
A voltage placed across the gap between the two d shaped magnets is used to accelerate the particles
106
What happens if a high energy proton collides with a stab,e element?
A radioactive isotope is produced
107
What are small cyclotrons used in hospitals for?
To produce the short lived isotopes needed in PET scanners
108
What is the difference between an elastic and inelastic collision?
Momentum is conserved in both however kinetic energy is not conserved in an inelastic collision but is conserved in an elastic collision
109
What is anti-matter?
Matter that has particles of the same mass and properties but opposite charge
110
What happens when an electron and positron collide?
Annihilation occurs and two gamma rays are produced moving in opposite directions
111
What is mass-energy equivalence?
It means that the masses of the annihilated positron and electron are converted into an equivalent amount of energy
112
What is the energy equivalent of an electron?
8 x 10^-14 J
113
What is the amount of energy released in positron-electron annihilation?
1.6 x 10^-13 J
114
How is annihilation used in PET scanners?
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
What is absolute zero?
-273 degrees - the temperature at which the pressure of a gas would be at 0 and the particles wouldn't be moving
116
What is the kelvin temperature scale?
Temperature relative to absolute zero - (0 K)
117
How do you convert kelvin to Celsius?
From kelvin to Celsius: subtract 273
| From Celsius to kelvin: add 273
118
Why do gases need to be kept at a pressure above atmospheric pressure?
So that they can contain a bigger volume of gases
119
If the volume of a gas increases at a constant temperature, what happens in regards to pressure?
Pressure decreases
120
What is the equation that links volume and pressure?
V1P1 = V2P2
```
V = volumes in m^3
P = pressures in Pa
```
121
If temperature of a gas is increased at a constant pressure, what happens in regards to volume?
Volume increases
122
What is the equation that links temperature and volume?
V1 = V2T1 / T2
123
When calculating volume, pressures and temperature in terms of gas, what temperature scale do we use?
Kelvin
124
What is the equation that links pressure, volume and temperature?
P1V1 / T1 = P2V2 / T2
