Electricity...

“Understanding the movement of

electrons”

Energy v Matter

Q? Does electricity have mass or volume, is it a form of Matter?

• Can the mass of electricity be found, does an electrical charge occupy a certain amount of space?

• No, therefore electricity (like heat, light & sound) is a form of energy - not matter.

Energy vs Matter

• It is important to remember that electricity is form of energy not matter.

• Therefore, electricity is concerned with the behaviour of electrical energy (more than the movement of matter).

Laws of Electrical Charges

• Oppositely charged objects attract.

• Similarly charged objects repel.

• Charged objects attract neutral objects.

Atomic Theory Review

• The ‘quantitative’ relationship between protons & electrons determines the charge of a given material.

• A given substance is usually neutral because the number of electrons & protons are the equal.

Atomic Theory Review

• Different substances are made up of different kinds of atoms.

• Some atoms have a stronger hold on their electrons than others do.

• Therefore, when two different materials are rubbed together, the one with the strongest hold on its electrons will remove electrons from the other material.

Atomic Theory Review

• The material which gains electrons becomes negatively charged while the material that losses electrons becomes positively charged.

• A static charge is an excess or deficit of electrons.

Types of Electricity

• Static: “At rest” - when electrical energy remains stationary in/ on a charged object.

• Current: “Flowing” - the movement of electrical energy along a pathway or ‘circuit’.

Static Electricity

• Induction: process by which a charged object produces a charge in another object with out touching it.

• Conduction: process by which a charged object produces a charge in another object by touching it.

Electroscopes

• The Electroscope is a device that is used to test the presence and behaviour of a static charge.

• Pith ball Electroscope• Metal Leaf Electroscope

Current Electricity

• The movement of electrical energy along a pathway.

• A pathway for electrical energy is called a circuit. A circuit is closed when electricity is allowed to flow around it. When electricity is not allowed to flow around a circuit it is considered open.

Circuits

• Series: A circuit where there is only one path for electricity to flow. All of the devices on a series circuit share electrical energy.

The Series Circuit

•Electrical devices are connected along one path.•Voltage is shared between all devices.

•Amperage is not shared between the devices.

Circuits

• Parallel: here there is more than one path for energy to take. The electrical devices are ‘independently’ connected & therefore do not share electrical energy.

The Parallel Circuit

•Electrical devices are connected along more than one path.

•Voltage is not shared between all devices.

•Amperage is shared between the devices.

Voltage (V)

• In order for an object to move there must be a force applied to make it move.

Voltage (V)

• As far as electricity is concerned the force that pushes electrons around a circuit is voltage.

• Voltage refers to the amount of ‘push’ electrons have in a circuit.

Current/ Amperage (I)

• Amperage (Amps) is the unit used to measure the flow of current in an electrical circuit.

• It refers to the number of electrons that pass a specific point in the circuit over a given time.

Resistance (R)

• Refers to slowing, hindering or “resisting” the flow of electrical energy.

Resistance (R)

• Resistance is used to turn electrical energy into another form of energy (heat, light, sound) through some kind of device.

• Examples: toaster, door bell or stereo.

Ohm’s Law (I=V/R)

• The amount of current that will flow through a circuit depends directly upon the voltage & resistance.

• The relationship between current, voltage & resistance is known as Ohm’s Law.

Electrical Efficiency