• How to determine the power of the current?

    Tatyana Goenko
    Tatyana Goenko
    January 22, 2013
    20942
    How to determine the power of the current?

    Electric current can be compared with how water flows in a pipe, and voltage with the level of this water. An electric current, passing through the pipe, does a certain job. Based on the definition, power is work per unit of time or speed of work.

    In one second, a certain amount of electricity passes through the cross section of the chain. 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 power

    Measured electrical power in watts (W). 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 power of a current, it is necessary to use the following formula: P = U * I (A), where U, I is the voltage of the electric field and the current, respectively, and P is its power.

    To understand how to properly use the formula, consider a small example.Suppose a voltage is applied to a resistor of 150V and a current of 0.2A flows through it. What is the power developed on this resistor? P = 150 * 0.2 = 30W.

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

    Now let's substitute the formula (B) into the formula (A) and get the formula (B): P = I2R (B). Suppose that a resistor with a resistance of 5 ohms passes a current of 0.5 A with a force of 0.5 A. Determine the power that is lost in the rheostat? P = 0.52* 5 = 1.25W.

    If the current is unknown to us, but we know the voltage and resistance, it is also possible to determine the power. From Ohm's law I = U / R, then using the formula (A) the power of the current is: P = U2/ R (Y)

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

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


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