Topic 5 - Electricity and Magnetism

Definitions for Topic 5 - Electricity and Magnetism: 5.1 - Electric fields 5.2 - Heating effects of electric currents 5.3 - Electric cells 5.4 - Magnetic effects of electric currents

Coulomb (the unit of charge)

The charge is transported by a current of one ampere in one second. Unit: As

Electric field strength

The electric field strength at a point is the force per unit charge experienced by a small positive point charge placed at that point

Drift speed

The speed at which charge carriers move along a conductor

Potential difference (pd)

Potential difference between two points I the work done when moving a unit of charge between the points

Electronvolt (eV)

The energy gained by an electron when it moves through a potential difference of one volt

1.6*10^-19 J

Resistance

The opposition to charge flow in an electrical circuit

Ohm’s law

The current through a conductor between two points is directly proportional to the potential difference between the two points

The resistance is constant as the current changes (ohmic conductors)

Resistivity

A fundamental property of a material that shows how well the material conducts electricity

Low resistivity means that the material is a good conductor

Kirchhoff’s first law

The total charge flowing into a junction is equal to the total charge flowing out

Kirchhoff’s second law

The total electromotive force around a closed circuit loop is equal to the sum of the potential differences around the loop

Electric cell

An electric cell is a device that converts chemical energy into electrical energy = the cell is discharging

When electrons pass through a cell, chemical energy -> electrical energy

When electrons pass through a resistor, electrical energy -> other forms of energy

Electromotive force (emf)

The work done per unit charge when moving charge between the terminals of a cell

Internal resistance

Resistance of components within the cell itself, leading to energy losses in the cell

Right-hand corkscrew rule

When our right thumb is pointing in the direction of the conventional current, our curling fingers show the direction of the magnetic field