Electric Circuits

Coulomb’s Law

Coulomb’s Law

Electric force between two point charges is proportional to magnitude of charges and inversely proportional to the square of the distance between them

Two Point Charges…

Experience equal magnitude of force but in opposite directions

Electric Field

Regions of space surrounding a charged particle where charged objects experience electric force.

More Dense E Field Lines

Stronger field strength

Less Dense E Field Lines

Weaker field strength

E Field Direction

Direction of force on positive test charges

Right Angle

Angle at which electric field lines enter/leave a surface

E

Electric field symbol

Newtons per Coulomb

Electric field unit

Energy

Ability to do work

Work

The energy transferred/transformed over a distance

Electrical Potential Difference

Work done by electric field to move charged particle per unit of charge (V)

Electronvolt (eV)

Work done in moving an electron through a potential difference of 1V

Electrical Current

Charge flowing past a point per second

Electrical Current Units

Amperes (A)

Electrical Current Symbol

I

Conventional Current

Direction that positive charges flow

Electron Current

Direction that negative charges flow

Magnet Field

Flow from north pole to south pole

Magnet Particles

Majority of particles have electrons moving in same direction

Magnetic Field Symbol

B

Magnetic Field Units

Tesla (T)

Direction of Magnetic Field Current

Flow of current is clockwise if wire is down, anticlockwise if wire is up

Magnetic Field Conventions

X is into page, dot is out of page

Resistance

Difficult an electrical current experiences in travelling between two points

Resistance Symbol

R

Resistance Units

Ohms

Ohmic Conductors

Components that have a stable resistance and hence follow Ohm’s Law, linear graph

Power

Rate at which energy is transformed

Power Symbol

P

Power Units

Watts (W)

Kilowatt Hours

Amount of energy transformed by a component of power rating 1kW used for an hour (3,600,000J)

Efficiency

Useful energy divided by total energy x 100%

Resistor

Light

Diode

Light Emitting Diode

Voltmeter

Ammeter

Fuse

Capacitor

Series Connection

Current passes through both components

Parallel Connection

Current splits into different paths

Composite Connection

Both series and parallel

Kirchoff’s Current Law

Sum of currents flowing into junction equals sum of currents flowing out of junction

Kirchoff’s Voltage Law

Voltage between two points in circuit is same regardless of path travelled

Series Features

Equal current but split voltage through components

Parallel Features

Equal voltage but split current through components