Brainscape's Knowledge GenomeTM

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


See full index

PHYSICS 160 > Section 2: Electricity > Flashcards

Section 2: Electricity Flashcards

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

Unit of charge

A

Coulomb (C)

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

+ve and -ve charges - cancel out?

A

+ve and -ve charges DON’T cancel out

The effects of the +ve and -ve charge can cancel out

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

Rubbing/contact between two objects causes…

A

Charges from one object to transfer to the other object (either +ve or -ve charge can transfer)

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

Conservation

A

Electrical charge is conserved

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

Grounding / earthing

A

Connecting an electrically charged object to the ground with a wire (or a water film) will result in the object losing its electric charge

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

Which charge can flow through a metal wire

A

Electrons (-ve charge)

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

Coulomb’s law in a vacuum

A

The size of the electric force between 2 point charges in a vacuum is given by Coulomb’s law
An inverse square law; strength of force depends on 1/r^2

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

Superposition principle

A

If there’s more than 2 charges, the 3rd charge doesn’t affect the force acting between the 2 charges (i.e. not affecting by ‘extra’ charges)

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

Field

A

A quantity that varies in space

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

Electric fields are…

A

Vector fields

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

Electric fields - units

A

N/C (newton/coulomb)

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

Direction of electric fields

A

The direction a positive charge will move

Negative charges go in opposite direction to field

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

Electric field lines

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
14
Q

Electric shielding

A

An object can be ‘shielded’ from an external electric field by enclosing it in a metal can
If metal can is exposed to an external electric field, the e- in the metal can will move and arrange themselves so there is no electric field in the can

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

What is voltage (V)

A

The electrical potential energy per coulomb of charge

Always measured with respect to something

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

What does it mean if 1C of charge changes 6V from point B to A

A

1C of charge at A has 6J more electrical PE than at B

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

When a charge is moved against an electric force…

A

Work is done on the charge –> causes charge to gain potential energy

18
Q

Millikan’s oil drop experiment

A

Weight force and electrostatic force on charge (oil drop) act in opposite directions
If V is adjusted until the drop is stationary, these 2 forces are balanced

19
Q

Equipotential surface

A

A surface perpendicular to the field lines

Electrical PE is constant

20
Q

Strength of fields and equipotential surfaces

A

In a strong field, the field lines are close tgt and so are the equipotential surfaces

21
Q

Capacitance (C) - units

A

Farad (F)

One farad = one C/V

22
Q

What is a capacitor

A

A device that stores electric charge

Made of a pair of conductors separated by an insulator

23
Q

What is capacitance (C)

A

The property of a capacitor to store charge

Increased C –> more charge the capacitor can store for a given applied V

24
Q

Ways to increase capacitance

A

Increase SA of plates - can store more charge on plates
Decrease distance between plates - stronger attraction of e- to +ve plate and cancels out more -ve charge repulsion
Put insulator between plates (dielectric)

25
Q

Dielectric strength

A

The max electric field a dielectric can withstand before breaking down and conducting

26
Q

Dielectric constant

A

When a dielectric is placed in an electric field, the dielectric polarises
The electric field created by the dielectric polarising (E_polarised) creates an opposite electric field to the applied electric field –> net electric field is smaller than applied electric field

27
Q

What is κ (kappa)

A

Dielectric constant - how many times the electric field is weaker in the dielectric compared to what it would be if no dielectric is present (i.e. vacuum)

28
Q

What does the dielectric constant (κ) depend on

A

The material between the capacitor plates

29
Q

Cell

A

A single chemical unit that makes electricity

30
Q

Battery

A

Several cells connected in series, so their voltages are added tgt

31
Q

Electric current

A

The rate of flow of charge

Amount of charge going through a given X-section of a conductor in one second

32
Q

Direction of current

A

Direction of positive charge flow

33
Q

Ampere-hours

A

Measures the quantity of charge that a fully charged battery can supply
e.g. a 100Ah battery can supply 1A for 100 hours, or 10A for 10 hours

34
Q

Resistance

A

The opposition to current

35
Q

Resistance symbols

A

Box or jaggered line

36
Q

Amp (A) is equivalent to

A

C/s

37
Q

Resistance depends on…

A

Proportional to length
Inversely proportional to area
Proportional to type of material

38
Q

Resistors - series and parallel

A

Resistors in series add, so R total is greater than any one of the resistors
Resistors in parallel: R total is less than individual resistances

39
Q

Electrical power

A

How rapidly an electrical device can transfer electrical energy into other forms
Measured in W = J/s

40
Q

R = R₀ [1 + α(T - T₀)]

A 
R = resistance at temp T
R₀ = resistance at temp T₀
α = temp coefficient of resistivity - can be +ve or -ve
41
Q

EMF of battery

A

Voltage measured when no current is being pulled out of battery

42
Q

Voltmeter, ammeter and resistance

A

A voltmeter should have high resistance so almost no current flows through it
An ammeter should have low resistance so there’s almost no voltage drop across it

PHYSICS 160 (5 decks)

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