Power And Voltage Formula

Power is measured in units of watts w where a watt is equal to a joule per second 1 w 1 j s.

Power and voltage formula. By ohm s law v ir and so there are additional forms of the electric power formula for resistors. An electric machine makes use of 300 j of energy to do work in 10s. The standard metric unit of power is the watt. For example in an open circuit condition voltage is present but there is no current flow i 0 zero therefore v 0 is 0 so the power dissipated within the circuit must also be 0 likewise if we have a short circuit condition current flow is present but there is no voltage v 0 therefore 0 i 0.

Power formula 1 electrical power equation. Power voltage current resistance p v i r calculator. Electric power is the rate per unit time at which electrical energy is transferred by an electric circuit the si unit of power is the watt one joule per second. The power formula is used to compute the power resistance voltage or current in any electrical circuit.

Power p i v r i 2 v 2 r where power p is in watts voltage v is in volts and current i is in amperes dc. If there is ac look also at the power factor pf cos φ and φ power factor angle phase angle between voltage and amperage. This calculator is based on simple ohm s law as we have already shared ohm s law p i v r calculator in which you can also calculate three phase current. But we have designed this one especially for dc circuits as well as work for single phase ac circuits without power factor.

They are power p or w measured in watts voltage v or e measured in volts current or amperage i measured in amps amperes and resistance r measured in ohms. In this calculator table you may enter two of the four factors in ohm s law. In the above circuit we know we have a battery voltage of 18 volts and a lamp resistance of 3 ω. How to use ohm s law to determine current.

For example if you have a 0 85 power factor 1 5 kw of power and a voltage of 230 v simply quote your power as 1 500 w and calculate. Learn the power formula. Power within an electrical circuit is only present when both voltage and current are present. P v i.

We ve seen the formula for determining the power in an electric circuit. If your power is in kilowatts i e thousands of watts it s best to either convert it to watts by multiplying by 1 000 or keep it in kilowatts make sure your voltage is in kilovolts kv volts 1 000. You can use ohm s law to express either voltage or current in terms of the resistance r in the circuit. Work done w 300 j time taken t 10 s.

Electric power is usually produced by electric generators but can also be supplied by sources such as electric batteries it is usually supplied to businesses and homes as domestic mains electricity by the electric power industry. V i r. For any circuit element the power is equal to the voltage difference across the element multiplied by the current. By multiplying the voltage in volts by the current in amps we arrive at an answer in watts let s apply this to a circuit example.