Power is the amount of energy per second that your circuit needs. An electronic circuit releases that energy mostly by doing useful work and generating heat. Fortunately, it’s easy to calculate the amount of energy consumed by your circuit.
Power is a function of both voltage and current in Watt’s. To get the energy used by a circuit use the following formula:
In this generalized formula, P is power in Watts, V is voltage in Volts, and I is current measured in Amps.
Power calculation example
In the circuit below we have a single 10kOhm resistor and a +12V DC voltage source.
If we now apply Ohm’s Law we find the amount of current running through the circuit.
So now we have the current, we can finally calculate the energy consumed by this circuit by applying the equation:
It is probably easier to calculate the example above by directly combining the formula with Ohm’s law. So then you get: