Topic 2 Electricity Within a Circuit

Static and Current Electricity: When charged particles build up in an object it is called static electricity. Another kind of electricity occurs when electrons flow in a current. A battery and wires can make current flow

What is an electric current? An electric current is the flow electrons flowing through wires and components. + - In which direction does the current flow? from the Negative terminal to the Positive terminal of a cell.

Current Electricity As electrons pass through the wire and into the light bulb, the filament lights the bulb

simple circuits simple electric circuit: It has a cell, a lamp and a switch. Circuit: components are connected together with metal wires cell lamp switch wires

simple circuits When the switch is closed, the lamp lights up. This is because there is a continuous path of metal for the electric current to flow around. If there were any breaks in the circuit, the current could not flow.

circuit diagram: cellswitchlampwires Scientists usually draw electric circuits using symbols;

circuit diagrams In circuit diagrams components are represented by the following symbols; cellbatteryswitchlamp motorammetervoltmeter buzzer resistorvariable resistor

measuring current Electric current is measured in amps (A) using an ammeter connected in series in the circuit. A

measuring current A A This is how we draw an ammeter in a circuit. SERIES CIRCUIT PARALLEL CIRCUIT

Lets give electrical diagrams a whirl…

Consider this to be a Switch

A

A

measuring voltage The ‘electrical push’ which the cell gives to the current is called the voltage. It is measured in volts (V) on a voltmeter. It provides the energy for the moving electrons. Voltage is also referred to as “Potential Difference” V

Different cells produce different voltages. The bigger the voltage supplied by the cell, the bigger the current. measuring voltage Unlike an ammeter a voltmeter is connected across the components Scientist usually use the term Potential Difference (pd) when they talk about voltage.

Thinking of Electricity like Water Current Current is literally just the amount of water flowing through a channel. - This is analogous to electricity flowing through a wire Less water means less water molecules are flowing More water means more water molecules are flowing

Amps (or amperes) Amps (or amperes) measures current – the amount of electricity flowing through some point. Amperes are measured in coulombs per second. Just like measuring amps of electricity, you could set up a flow meter to measure exactly how much water is flowing past this point

Volts Voltage is analogous to water pressure Voltage is the force that moves the electrons through the wire. Increasing voltage increases current (electron) flow water which falls from a high waterfall has more pressure than water which falls over the edge of small rocks

Watts Watts = A measure of power / the rate of energy consumed by an electrical device when it is operating Watts are calculated by multiplying the voltage at which an appliance operates (i.e. 1.5 V) by the current it draws