The previous diagram does not show an ohmmeter because, in most cases, resistance should only be measured when a circuit is not or fully ‘on’ connected. To use an ohmmeter, you would place it a component in parallel, ‘across’ – just like a voltmeter. Components There are lots of different components which can be used to make circuits, the ones which will often feature in National 5 Physics are shown in the table below. Component Name Circuit Symbol Function Supplies electrical energy to a circuit, the Cell longer line shows the positive side. Battery A battery of means 2 or more cells. Supplies electrical energy to a circuit in the DC Supply form of a direct current. Supplies electrical energy to a circuit in the AC Supply form of an alternating current. A lamp lights when current flows through Lamp it, converting electrical energy to light energy. A switch allows you to complete or break a Switch circuit. A resistor restricts the flow of current, this Resistor may be to protect other components. A resistor, the resistance of can be Variable Resistor varied in the circuit, could be used for a dimmer switch. LDR Can be used to control a circuit. The (Light Dependent resistance goes down as the light Resistor) increases.
The previous diagram does not show an ohmmeter because, in most cases, resistance should only be measured when a circuit is not ‘on’ or fully connected. To use an ohmmeter, you would place it ‘across’ a component – in parallel, just like a voltmeter. Components There are lots of different components which can be used to make circuits, the ones which will often feature in National 5 Physics are shown in the table below. Component Name Circuit Symbol Function Cell Supplies electrical energy to a circuit, the longer line shows the positive side. Battery A battery of means 2 or more cells. DC Supply Supplies electrical energy to a circuit in the form of a direct current. AC Supply Supplies electrical energy to a circuit in the form of an alternating current. Lamp A lamp lights when current flows through it, converting electrical energy to light energy. Switch A switch allows you to complete or break a circuit. Resistor A resistor restricts the flow of current, this may be to protect other components. Variable Resistor A resistor, the resistance of can be varied in the circuit, could be used for a dimmer switch. LDR (Light Dependent Resistor) Can be used to control a circuit. The resistance goes down as the light increases.
electricity_summary_book.docx