Measure of voltage
How do you measure voltage in a circuit?
Yes, you need to use a voltmeter or a multimeter with a voltage scale.
Voltage is always measured with respect to 2 points in an electrical circuit.
Most DC circuits use a common output of the power supply(usually the negative) for one of the points and call this ground (abbreviated GND). The black terminal of your meter should be attached to this point, while the red lead is used to measure voltages in the rest of the circuit with respect to this ground point.
AC circuits also use a common ground point but the polarity of the leads is not as critcal since AC voltage doesn’t have a “polarity”.