Brainscape's Knowledge GenomeTM

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


See full index

Imaging Technology > Electricity > Flashcards

Electricity Flashcards

1
Q

What is a vacuum?

A

No matter in a volume of space
Like charges repel
Unlike charges attract
Attraction is effected by distance

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

Charges flow in materials

A

When charges move, they produce a magnetic field, moving anticlockwise

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

Like charges

A

Repel, force is positive

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

Unlike charges

A

Attract, force is negative

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

What is the force equation?

A

Product of the charges divided by the distance squared

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

What is the SI unit for charge?

A

Coulomb

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

Explain a focusing cap on an X-ray tube

A

To keep the electrons focused on the target anode, and thus creating a sharper image. Keeping the flow of electrons repelling and confined in the area of movement towards the target.

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

Define electrical potential

A

Work done in moving a unit charge from infinity to that point

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

What is the SI unit for electrical potential

A

Volt

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

Define potential difference

A

The difference in work done moving a unit charge from one point to another

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

What is electromagnetic force (EMF)

A

The driving force across a power source (negative charge flows from a negative to positive potential)

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

Conduction band

A

Free electrons

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

Forbidden zones

A

Electrons cannot travel freely

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

Valence band

A

Electrons can freely move from the outer shell

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

Filled band

A

Complete shells

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

Insulators

A

Require more energy for electrons to enter conduction band as the forbidden zone is larger
Must increase temperature and Voltage

17
Q

Semi-conductors

A

Requires less energy as the forbidden zone is shorter
At an increased temperature, more electrons will enter the conduction band, but at room temperature some will enter anyway

18
Q

Conductors

A

No forbidden zone, so electrons can freely pass through bands (random movement)

19
Q

What happens as charge storage increases?

A

Repulsive effect slows down storage
To increase, increase the size of the storage capacitator, or the potential difference

20
Q

What is capacitance?

A

The quantity of charge which can be stored on a conductor per unit potential

21
Q

What is the SI unit for capacitance?

A

Farad

22
Q

What is a capacitor?

A

A device used to store electrical current, consists of two electrode conductors and a separating insulator

23
Q

What does the insulating layer do in a capacitor?

A

Prevents contact between the two plates, thus preventing charge flow
Increases the capacitance of the capacitor

24
Q

What effects capacitance?

A

Distance between plates
Area of plates

25
Q

Uses of capacitors

A

Voltage smoothing (overcomes X-ray energy fluctuations)
Timing circuits (signal sent to end exposure when capacitor reaches max)

26
Q

State some facts about electron flow

A

Direction of movement is equally random
Resistance to flow is affected by temperature due to increased collisions

27
Q

What is electrical current?

A

Flow from negative to positive

28
Q

What is convectional current?

A

Flow from positive to negative

29
Q

What is the SI unit for current?

A

Ampere

30
Q

How do you work out the electric charge flowing through an X-ray tube during an exposer?

A

milliamps x time(s)

31
Q

What is the SI unit for resistance and what is resistance?

A

Ohms
Collisions between vibrating electrons

32
Q

What factors affect resistance?

A

Length
Cross sectional area
Conductor or insulator?
Temperature

33
Q

What is Ohm’s Law?

A

The current flowing through a conductor is directly proportional to the potential difference between its ends

34
Q

What is the equation for Potential Difference?

A

V + I x R
(V=potential difference
I= current
R= resistance)

35
Q

What is electrical power?

A

The rate of doing work
Power= voltage x current

36
Q

How do you minimise power loss?

A

High voltage and low current

37
Q

How to reduce resistance?

A

Copper
Increase cross sectional area

38
Q

Electrical safety features

A

Isolation
Insulation
Earthing
Restricted access

Imaging Technology (7 decks)

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