Determine Current using Ohm's Law

To determine the current in a portion of a circuit, Ohm's law can be applied. In this case, the current is being determine to find an appropriate transistor. So, prior to adding the transistor, the current is found and the transistor with at least that current rating can be selected.

Ohm's Law: Current = Volts/Resistance I = V/R Example: I = 5v / 25 ohms = .2 amps