Electrical Theory

Kirchhoff's Law: What goes into a circuit (both voltage and amps) must flow out

Measuring Voltage

Put multimeter at the opposite ends, lining up the ground on the multimeter with the negative side of the power source and lining up power with the positive side of the power source. Make sure that the multimeter is set to measuring volts.

Measuring Resistance

Since resistors do not have polarity, the positive or the ground on the multimeter can be used to measure either side of the resistor. The multimeter will send some current through the resistor and displays the output as the difference between the original current input and what it gets back. On the older multimeters, make sure that the multimeter is set to measuring ohms (the unit of resistance).

Measuring Current

The current measurement varies based on what is drawing current. For example, the current in a circuit including an LED and a lamp would be different. The circuit with an LED would have less current, while a circuit with a lamp would draw more current because it is less energy efficient.

Do not try to measure current through something that draws current or supplies power. This may fry the component. To measure current, complete the circuit. Refer to the below diagram.