MSSC Maintenance Awareness Practice Test

Power in an electrical circuit is the rate at which energy is transferred, found by multiplying the voltage by the current. This gives P = V × I, with watts equal to volts times amperes. If voltage is labeled as E in your material, then P = I × E expresses the same relationship, so it aligns with the standard concept that power comes from the combination of voltage and current. The form P = E × R isn’t a general power expression, since multiplying voltage by resistance doesn’t yield power on its own. For resistor-focused forms, you’d use P = I²R or P = V²/R, which you can obtain from P = VI together with Ohm’s law V = IR.