Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physics extension edexcel > P3.2 X-rays and ECGs > Flashcards

P3.2 X-rays and ECGs Flashcards

You may prefer our related Brainscape-certified flashcards:
Physics 101 flashcards AP® Physics flashcards
1
Q

What does ionising radiation do?

A

Turn atoms into ions by removing some of their outer electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What happens when the energy of an X-ray increases?

A

It becomes more ionising

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How do you increase the energy of an X-Ray?

A

You increase its frequency and voltage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is a negative electrode called?

A

A cathode

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is a positive electrode called?

A

An anode

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What happens when you heat the cathode in an X-ray machine?

A

It becomes an electron gun

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the process of an electron gun emitting electrons called?

A

Thermionic emission

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What happens when there is a large potential difference between the anode and the cathode?

A

The electrons accelerate towards the anode

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Why does an X-ray machine have an evacuated tube?

A

So that the electrons don’t collide with other particles as they cross the tube

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is an evacuated tube?

A

A tube from which the air has been removed so that there is a vacuum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What happens to the kinetic energy of electrons when they hit the anode?

A

Most of it is transferred to thermal energy, but some are transformed into X-rays

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How do you increase the amount of X-rays?

A

You make the coil hotter (cathode) so that more electrons are emitted from the electron gun

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is another name for an X-ray machine?

A

X-ray tube

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

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

A
  • to reduce wear

- to prevent it from overheating

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

At what angle are X-rays emitted to the electron beam?

A

90 degrees

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is current?

A

The rate of flow of electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How do you find current?

A 
I = N x q
Current = number of particles flowing each second x charge on each particle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How do you find the kinetic energy of an electron?

A

E = 1/2mv^2 or E =eV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What does m stand for in the formula used for finding kinetic energy?

A

Mass of an electron in kg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What does v stand for in the formula used for finding kinetic energy?

A

Velocity of the electron in m/s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is kinetic energy measured in?

A

Joules or kgm^2/s^2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What does V stand for in the formula for finding kinetic energy?

A

Potential difference in volts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What does e stand for in the formula for finding kinetic energy?

A

Charge of an electron

24
Q

What is the charge of an electron?

A

1.6 x 10^-19 C

25
Q

When you double the distance away from a radioactive source, what happens to its strength?

A

It decreases to a quarter

26
Q

How do you find out how the strength of a radioactive source changes in relation to distance?

A

By using the inverse square law

27
Q

What does the inverse square law state?

A

The strength of a wave is inversely proportional to the square of the distance from the source

28
Q

When the density of a material increases, what happens to the amount of X-rays it absorbs?

A

It increases

29
Q

Why does bone show up lighter on an X-ray than organs or tissues?

A
  • Bone is denser than organs or tissues so it absorbs more X-rays
  • on X-rays dark areas are where a lot of X-rays have been detected
  • because the bone has absorbed a lot of X-rays not many are detected by the scanner
  • this means it shows up as white because of negative imaging
30
Q

How does a computer build up a 3D image from a CAT scanner?

A

It builds up many cross-sectional views of the body gotten from the scanner

31
Q

What do unusual areas of brightness or darkness indicate on a CAT scan picture?

A

Tumours or small areas of tissue that have died because their blood supply has been obstructed

32
Q

What do fluoroscopes do?

A

Show a patient’s organs working

33
Q

What can fluoroscopes be used for?

A

Detecting blocked blood vessels

34
Q

How does a fluoroscopy get a moving image of the inside of the body?

A

It uses an X-ray detector attached to a digital video camera. The patient is put between this and the source

35
Q

What are the benefits of CAT scans and fluoroscopes?

A
  • painless for the patient
  • non-invasive
  • no biopsy
36
Q

How is the risk of damaging other tissues minimised when treating cancer with X-rays?

A

They’re fired from several different directions so that only the tumour receives a high dose

37
Q

What is an action potential?

A

An electrical signal that is sent to each muscle cell to tell it when to contract

38
Q

Why does the human body conduct electricity?

A

It contains a high proportion of water with dissolved salt in it

39
Q

What does ECG stand for?

A

Electrocardiogram

40
Q

What is an ECG?

A

A picture of the heart’s electrical signals

41
Q

What does an ECG show?

A
  • how fast the heart is beating

- which part of the heart might not be working properly

42
Q

How much time is one large square on an ECG equal to?

A

0.2 seconds

43
Q

How do you find out the frequency of a heart beat in beats per second?

A 
f = 1/t
frequency = 1 / time period in seconds
44
Q

How do you find the time period of a heart beat?

A

You work out the average length of one heartbeat

45
Q

How does one action potential spread across the heart?

A
  • the sino-ventricular node contracts
  • the action potential spreads across both atria
  • the atrio-ventricular node contracts
  • the action potential spreads up the ventricle walls
  • a contraction spreads up from the base of the ventricles
46
Q

What is the frequency of a heart beat usually given as?

A

bpm, beats per minute

47
Q

What is pulse oximetry used for?

A
  • measuring the pulse rate of a person

- seeing how much oxygen their blood is carrying

48
Q

What does a pulse oximeter consist of?

A
  • a LED emitting red light
  • a LED emitting infrared
  • a detector
49
Q

What does LED stand for?

A

Light emitting diode

50
Q

What does oxygenated blood absorb more of in comparison to deoxygenated blood in a pulse oximeter?

A

Infrared

51
Q

What does deoxygenated blood absorb more of in comparison to oxygenated blood in a pulse oximeter?

A

Red light

52
Q

How does a pulse oximeter work out a pulse?

A

Each beat of the heart causes a surge of oxygenated blood, so the oximeter looks at the peaks of infrared absorbance

53
Q

How does a pulse oximeter work out how much oxygen the blood is carrying?

A

By comparing the absorbance between the red light and infrared LEDs

54
Q

How is the amount of oxygen the blood is carrying expressed in an oximeter?

A

As a percentage of its maximum

55
Q

What does a pacemaker do?

A

Detect, amplify and transmit action potentials to other parts of the heart so that its chambers contract correctly

56
Q

What can be used when someone’s heart doesn’t beat properly?

A

A pacemaker

57
Q

Where do you put a pulse oximeter?

A

A finger or a toe

Physics extension edexcel (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions