6.2 Measuring electricity

What we are learning about 1.What is current, voltage and resistance? 2.How are they measured? 3.What is the relationship between current, voltage and resistance in series and parallel circuits?

The components are connected end-to-end, one after the other. They make a simple loop for the current to flow round. SERIES CIRCUITS If one bulb ‘blows’ it breaks the whole circuit and all the bulbs go out.

PARALLEL CIRCUITS The current has a choice of routes. The components are connected side by side. If one bulb ‘blows’ there is still be a complete circuit to the other bulb so it stays alight.

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

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

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 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.

measuring voltage V This is how we draw a voltmeter in a circuit. SERIES CIRCUITPARALLEL CIRCUIT V

Activity Book 6.3 – Reading meters

Prac – Dry Cell Voltages

Mains Supply Voltage - AC Voltage is a measure of the ‘push’ that the electrons get from the power supply. Using p191 to help, copy and complete the table below. ApplianceSupply voltage (V) laptop phone digital camera

Batteries - DC Wet Cell Dry Cell

Batteries - DC Photovoltaic cells

Resistance Resistance is a measure of how difficult it is for a electrons to pass through a material or component. The energy(voltage) lost by the electrons as they travel through a material depends on the resistance of the material. As resistance increases so does the current.

Activity Book 6.3 and 6.4

Conductors and Insulators Using p194 to help you find some examples of insulators, copy and complete the table below. ConductorInsulator

Unit Review 6.2