Physics - Electricity & Electromagnetism

Ammeter function

Measures current

Voltmeter function

Measures voltage

Cell/Battery function 

Provides voltage 

Resistor function 

Adds resistance 

Current

Flow of electric charge

Current unit

Ampere(A)

Current symbol

I

What is voltage also known as

potential difference

Voltage

Energy per unit of charge

Voltage unit 

Volts(V)

Voltage symbol 

V

Resistance

How much the circuit resists the flow

Resistance unit

Ohms

Resistance symbol

R

Power

Rate of energy transfer

Power unit 

Watt(W)

Power symbol 

P

Charge

Amount of electrical charge

Charge unit

Coulomb(C)

Charge symbol

Q

Energy

Amount of electrical energy transfered

Energy unit 

Joules(J)

Energy symbol 

E

Ohm’s Law 

V=IR

Power equation (Voltage and Current) 

P=VI

Power equation (Current and Resistance)

P=I²R

Power equation (Voltage and Resistance)

P=V²/R

Energy in terms of Charge and Voltage

E=QV

Total resistance (series)

R_total = R₁ + R₂ + R₃

Total resistance (parallel)

1/R_total = 1/R₁ + 1/R₂ + 1/R₃

Opposites always

Attract

Right hand rule, thumb

Direction of current

Right hand rule, fingers

Direction of field

Right hand slap rule, thumb

Direction of current

Right hand slap rule, fingers

Direction of field 

Right hand slap rule, palm 

Direction of force 

Direction of electric field from positive point 

Outwards 

Direction of electric field lines from negative point 

Inwards 

Do electric field lines cross

no

Where is electric field strongest

Where lines are most concentrated

Electric field strength equation

E=F/Q

Size of electric field equation 

E=V/d

Current equation

I=Q/t

Force on current carrying wire

F=BIL

Force on current carrying wire at angle to magnetic field

F=BIL*sin(angle)

B

Field strength

Direction of field/wire into page symbol

cross

Direction of field/wire out of page symbol

dot

Magnetic field unit 

Tesla(T)

Magnetic field symbol

B

Force experienced by moving particle in magnetic field 

F=Bqv

The direction o

Power in terms of Voltage and Current

P=VI

Induced voltage (wire moving through magnetic field)

V=BIL

Electric field unit

Volts per metre (Vm^-1)

Force experienced by a charged particle moving within an electric field

F = qE

Force experienced by a charged particle moving within a magnetic field (1)

F = Bqv (1)

Impulse unit 

Newton Seconds 

Impulse symbol

J (Imp)

Induced current (velocity)

V = Bvl

What happens as a wire moves through a magnetic field

It cuts through the field lines

What happens to electrons in a wire as it cuts field lines 

They experience a magnetic force, making them move

Where do electrons move in a wire when experiencing a magnetic force 

To one end of the wire, making that end negatively charged, and the other end positively charged 

What happens when one end of a wire is negative and the other positive

There is a potential difference caused by charge separation between the ends, inducing voltage

Faraday’s law

The induced voltage is proportional to the rate of change of flux through the wire (V = B’v’l), higher speed gives a higher voltage 

What is magnetic flux 

A measurement of how much field is there is in an area 

Lenz’s law 

The direction of the induced voltage is always opposite to the charge which produced it

What happens when a charged particle moves closer to or further away from a plate generating a uniform electric field

Work is done either by the field or against the field depending on the direction of movement.

What happens when work is done on a charged particle against a field or by the field

The particles electric potential energy changes