Brainscape's Knowledge GenomeTM

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


See full index

AQA A-Level Physics > 7.0 Fields And Their Consequences > Flashcards

7.0 Fields And Their Consequences Flashcards

1
Q

What is a force field

A

A region in which an object feels a non contact force

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

Representation of a force field

A

By vectors in the direction of the field

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

Direction of field lines

A

From north to south

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

Similarities between gravitational and electrostatic forces

A

Both have inverse square laws, same field line characteristics, have potentials, and equipotential surfaces

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

Differences between gravitational and electrostatic forces

A

Masses always attract whereas charges may attract or repel

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

What is the inverse square law in fields

A

Where field strength and force decreases with the square of the distance

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

What fields do the inverse square law effect

A

gravitational and electric

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

What are field lines

A

A visual representation of a fields direction and strength

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

What does the width of field lines represent

A

The closer the field lines, the stronger the field

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

What is a uniform field

A

Field strength is constant, and the field lines are parallel and evenly spaced

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

What is a radial field

A

The field radiates outward or inward from a point source, and the field strength decreases with distance

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

What is potential energy in a field

A

The potential energy is the mass or charge has due to its position in a field

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

What is gravity

A

A universal force of attraction between all mass

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

What is gravitational potential

A

The work done per unit mass to move a small test mass from infinity to a point in a gravitational field

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

Why is gravitational potential zero at infinity

A

At infinite, the grav field becomes negligible, so the work done to move the test charge is zero

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

What is gravitational potential difference

A

The difference in gravitational potential between two points in the grav field

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

What is an equipotential surface in gravitational fields

A

Surfaces in a field where all points have the same gravitational potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Properties of equipotential surfaces

A

No work is done to move along them and they are always perpendicular to field lines

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

What is significant about the negative in the grav potential equation

A

shows that the potential is always negative, as gravitational forces always attract

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

relation of orbital period and speed to radius

A

the square of the period if directly proportional to the cube of the radius

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

What is the total energy of an orbiting body

A

it is always negative. the more negative, the lower the orbit

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

What is escape velocity

A

The minimum speed an object must have to leave a grav field without requiring additional energy

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

What must occur for escape in grav fields

A

the objects total energy must reach zero

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Letter for central body in grav fields

A

M

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Letter for object in grav fields

A

m

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is a synchronous orbit

A

An orbit of period of that of the rotational period of the body it orbits

27
Q

Characteristics of synchronous orbits

A

Object remains fixed relative to a point on the central mass

28
Q

Conditions for a synchronous orbit

A

planet must have a fixed rotational period, orbital period = rotational period, must be circular

29
Q

What is LEO

A

Low Earth Orbit. Between 200 - 2000 km

30
Q

Uses of LEO

A

Observation, scientific research, communication, surveillance

31
Q

Use of geostationary orbits

A

communication and weather monitoring

32
Q

Define coulomb’s law

A

The magnitude of the force between two point charges is directly proportional to the product of the charges and inversely proportional to the square of the distance between

33
Q

What is the permittivity of free space

A

the value of the absolute dielectric permittivity of a vacuum

34
Q

When calculating force between charges, what can we do

A

Treat air as a vacuum

35
Q

Where is charge concentrated in a charged sphere

A

Radiating out from the centre

36
Q

Compare the magnitude of gravitational and electrostatic
forces between subatomic particles

A

The electrostatic force is much greater than the gravitational force. Grav can be considered negligable in electrostatic calculation

37
Q

Define electric field strength

A

the intensity of an electric field at a particular point

38
Q

Define absolute electric potential

A

The work done per unit charge to move a small test charge from infinity to a point in an electric field

39
Q

Why is electric potential zero at infinity

A

At infinite, the electric field becomes negligible, so the work done to move the test charge is zero

40
Q

What is electric potential difference

A

The difference in electric potential between two points in the electric field

41
Q

What is an equipotential surface in electric fields

A

Surfaces in a field where all points have the same electric potential

42
Q

Define capacitance

A

The charge stored per unit potential difference

43
Q

What is a dielectric

A

an electrical insulator that can be polarised by an applied electric field

44
Q

How do dielectrics work

A

When in a field, the polarised molecules in the material rotating slightly to the opposite orientation to the field, creating another field that opposes the original one

45
Q

What is relative permittivity

A

the factor with which the electric field is decreased relative to vacuum

46
Q

What is the area below a charge - pd graph

A

The energy stored by the capacitor

47
Q

What is the time constant

A

RC

48
Q

What is the time to halve of a charged capacitor

A

0.69RC

49
Q

What is the force on a current carrying wire in a mag field

A

F = BIL when perpendicular to current

50
Q

Fleming’s left hand rule

A

Thumb: Motion, Index finger: Field, Middle finger: Current

51
Q

What is magnetic flux density

A

The strength of a magnetic field defined by the density of field lines

52
Q

Definition of the tesla

A

The flux density that causes a force of 1 N on a 1 m wire carrying a current of 1 A at right angles to the field

53
Q

What is the force on a charged particle moving in a mag field

A

F = BQv when field if perpendicular to velocity

54
Q

Direction of positively charged particle in mag field

A

With field lines

55
Q

Direction of negatively charged particle in mag field

A

Against field lines

56
Q

Uses of mag fields

A

Circular path in cyclotron

57
Q

Define magnetic flux

A

The number of field lines passing through a region of space

58
Q

Define magnetic flux linkage

A

The magnetic flux for a multiple turn coil

59
Q

What is electromagnetic induction

A

The process where an emf is induced from a change in flux on the material

60
Q

Define Faraday’s law

A

The magnitude of the induced e.m.f is directly proportional to the rate of change in magnetic flux linkage

61
Q

Define Lenz’s law

A

The induced e.m.f acts in such a direction to produce effects that oppose the change causing it

62
Q

Applications of electromagnetic induction

A

Electric generators, Induction motors, Induction cooking

63
Q
A

AQA A-Level Physics (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions