Question

Which of the following terms does not represent electrical power in a circuit?

A.)${I^2}R$
B.)$I{R^2}$
C.)$VI$
D.)$\dfrac{{{V^2}}}{R}$

Answer 1

Hint: In order to solve this question first we will define what electrical power is and then using ohm's law we will find all the formula related to electric power. Electric power can be said to be the rate at which energy gets transported to or from a part of an electric circuit.

Complete step-by-step answer:
Energy can be delivered by a battery or a circuit element, for instance, a resistor which releases energy as heat. For any element of the circuit, the power equals the difference in voltage across the element which multiplies by the current. If we look at it from the Ohm’s Law, we see that V = IR here, thus there are other forms of the electric power formula for resistors. We measure power in units of Watts.

Moreover, it is important to know that a Watt = Joule per second. (1 W = 1 J/s). Therefore:

P = VI

Over here,

P refers to the electric power
V is the voltage difference
I is the electric current

Then we have the formula for resistors which means, it combines Ohm’s law with Joules Law. Therefore, we have:

$
  P = VI{\text{ }}\left[ {V = IR} \right] \\
  P = {I^2}R \\
$

Also

$I = \dfrac{V}{R}$

$
  P = {\left( {\dfrac{V}{R}} \right)^2} \times R \\
  P = \dfrac{{{V^2}}}{R} \\
$

V refers to the difference in voltage \[\left( {V = J/C} \right)\]

I is the electric current \[\left( {A = C/s} \right)\]

R refers to the resistance \[\left( {\Omega = V/A} \right)\]

Hence the correct option is B.

Note- In order to solve these types of questions, you need to have a good concept of the basic formulas and must remember the law’s such as ohm’s law and the relation between the circuit parameters. Also, electrical power offers quite a low entropy kind of energy. Further, it can be carried through long distances. In addition, it can also convert to other types of energy like light, motion or heat.