# How to determine the power of the current?

Electric current can be compared with how it flowswater in the pipe, and the voltage with the level of this water. Electric current, passing through the pipe, performs a certain work. Based on the definition, power is the work per unit of time or speed of work performance.

For one second in the chain passes a certainthe amount of electricity through the cross-section of the circuit. This concept will be called the current strength. Therefore, there will be a directly proportional relationship between power, current and voltage.

## Formulas for calculating the current

Electric power in watts (W) is measured. The current in 1A and with a voltage of 1 V has a power of 1W. In order to find out how to determine the current power, it is necessary to use the following formula: P = U * I (A), where U, I is the electric field voltage and current strength respectively, and P is its power.

To understand how to properly useformula, consider a small example. Suppose a voltage is applied to a 150V resistor and a current of 0.2A is applied to it. What kind of resistor develops power? P = 150 * 0.2 = 30W.

There is another way to calculate the powerelectric current. If the resistance of the circuit and the current are known, then it is necessary to use Ohm's law (the formula for the chain segment is applicable): U = I * R (B)

Now substitute the formula (B) in the formula (A) and obtain the formula (B): P = I2R (B). Suppose that through a rheostat, whose resistance is 5 ohms, passes with a force of 0.5A current. Determine the power that is lost in the rheostat? P = 0.52* 5 = 1.25W.

If the current is not known to us, but we know the voltage and resistance, then it is also possible to determine the power. From Ohm's law I = U / R, then using formula (A) the current power is equal to: P = U2/ R (D)

The rheostat has a resistance of 5 ohms, and the voltage in it is 2.5V, then the power according to the formula (D) will be: P = 2.52/ 5 = 1.25W. If you know any two values from the formula for Ohm's law (if you consider the circuit portion), you can always determine the current power.

Recalling the definition of power, we can write another formula for its calculation: P = A / t (D), where P is the power, A is the work of the electric current, and t is the time during which this work is done.