When it comes to electrical circuits, there’s a lot to remember and understand. We've got you covered with this Intro to Circuits BBC Bitesize guide.

Any time the voltmeter probes see the same line (L1 to L1 or L2 to L2), 0 V will be read on the voltmeter because there is no voltage difference between the same lines. So, if the service technician ...

The resistor values (R1&R2) in the circuit diagram provide some over-voltage protection then measuring low voltages. Keep it in mind that any input voltage higher than about 55V could fry the Arduino.

This digital thermometer circuit diagram uses a common 1N4148 diode as the temperature sensor. The temperature coefficient of the diode, -2 mV/°C is. ... Set P1 so that the digital voltmeter will ...