This activity guides Scouts through how to use a multimeter to measure voltage, resistance and current. Scouts can also refer to the How does Electronics Work? section of their packs to help them undertand the basic concepts. The Scout Pack contains instructions on how to use a typical multimeter, but you should also refer to the instruction manual for the multimeter you are using if possible.
A variety of components can be used for this activity. These can be borrowed from other projects since they can all be re-used. The only important factors to bear in mind is that when using a 9V battery, any resistors used should be at least 100Î© and that an appropriate current limiting resistor (at least 330Î©) must be used for any circuits containing an LED.
â€¢ A multimeter
â€¢ Terminal block
â€¢ A battery clip
â€¢ 9V battery (these can be shared between groups)
â€¢ 330Î© resistor (a 470Î© resistor can be used as an alternative)
â€¢ Additional resistors of different values - must be 100Î© or above
â€¢ Light Dependent Resistors or other variable resistors (optional)
Multimeters can be damaged easily, so before Scouts start using one, you should explain how the multimeter they will be using works and make sure they familiarise themselves with the different settings.
A diagram of a standard multimeter is included in the Scout pack.
You will also need to remind them about current, voltage and resistance.
Make sure they follow these rules when using the multimeter:
â€¢ Always disconnect the multimeter before changing any settings
â€¢ Always check the settings before you connect to a circuit
â€¢ Never leave a multimeter set to a current range
Once the Scouts are familiar with the basics they can test some simple circuits using the multimeter. Some examples are given in the Scout pack. These can be modified using different values of resistors to encourage the Scouts to investigate for themselves. It is important that you check the circuits containing LEDs before they attach the battery. LEDs will explode if they receive too much current or too high a voltage.