Physics - Electrical Energy Yr 9

What is an electrical current?

An electric current is a flow of charged particles (electrons or ions) moving through an electrical conductor or space.

Electric charge

The charge of a subatomic particle.

Explain how electrons carry an electrical charge around a closed circuit

A chemical reaction inside the battery produces electrons that are propelled around a circuit from the negative to positive end, with like charges in subatomic particles repelling each other, creating a circuit.

Electrical Conductors

A type of material that allows the flow of charge (electric current) - Copper, silver, gold, steel, aluminium, water

Electrical Insulator

A type of material where electrical currents cannot flow - plastic, rubber, wood, glass

Explain how electrocution happens, and how it affects the human body

If the body meets live electricity, the electric current flows through the tissue in the body, which causes an electric shock. Injuries can be burns and internal tissue and organ damage.

Define static electricity

The imbalance between negative and positive charges in an object when the electrical charge builds up in a place without anywhere to move.

Define voltage

The pressure from an electrical current that pushes charged electrons through a circuit (Measured in volts (V) using a voltemeter)

Define current

The rate at which electrons flow past a point in a closed circuit (I)

Define resistance

A measure of the opposition to the flow of current in an electrical circuit (measured in Ohms (omega sign))

Amperes and amperage

The frequency of electron movement (how many electrons or charge passes a place in the wire per second) - Measured in Amperes or amps using an ammeter

List factors that affect the resistance of a material electrical

Depends on the material (metals have low resistance, rubber has high resistance), the shape of the materials (longer metal wire = more atoms to get past = greater resistance or thinner wire = less room for electrons to manoeuvre = greater resistance) and temperature (hotter = faster, colder = slower or more resistance) - lower resistance short and wide wires easy for electrons to flow

Describe cells

A cell is a device that is an electrical power supply that has two electrodes, with one end being positive and one being negative. This taking and giving of electrons allows charges to flow, creating an electrical current.

Describe batteries

A battery is an electrical power supply that contains a number of cells to convert chemical energy into electrical energy.

Describe wire

Gives electrons a path to move along when connected to a battery

Describe resistors

Placed in circuits to purposefully decrease the voltage to prevent overloading

Describe devices

Are motors, light bulbs and other devices that can be attached to circuits to use the kinetic of energy to create light, heat, movement or sound.

Series circuits

All circuit components are connected into a single loop which are all controlled by the same circuit, the total supply voltage is shared between the devices (dimmer light).

Parallel circuits

Circuits arranged into different sections, each device on its own branch receives full supply of voltage, adding devices with their own branches doesn’t affect intensity (bright light for all), each branch can have its own switch.

Discuss safety switches

To protect people from electric shock, electricity can be turned off very quickly to prevent damage.

Discuss fuses

A type of wire with high resistance and a low melting point to protect a system from overload and short circuit faults but cutting off power to them.

Discuss ground in plug

If a malfunction or damage occurs, the ground wire is an emergency path that protect you and your devices from electric shock by taking the electric current to the ground in case of a fault.