Question

which of the following expression does not represent the electric power in the circuit a. Vi b. 12/R c. V2/R d. 12R​

Answer 1

b). Part (1^2/R) is the expression that does not represent electric power.

Answer 2

Answer:

The expression for electric power will be:

$P=VI$  or   $P=\frac{V^{2}}{R}$    or   $P=I^{2}R$

Therefore, option (b) does not expression represent electric power.

Explanation:

The electric power is the work done per unit time. It has S.I. unit Watt. The formula of power is :

$P=\frac{w}{t}$                                                                             ...........(1)

Where w is the work done and t is time.

Potential difference is the work done to bring a charge to a particular point from infinity.

$V=\frac{w}{Q}$

$w=VQ$

Put the vale of w in equation (1)

$P=\frac{VQ}{t}$                                                                           .............(2)

We know that the current is the charge passing through a conductor in per unit time.

$I=\frac{Q}{t}$    

Put the value of $I$ in eq.(2):

Therefore, power $P=VI$                                               ............(3)

From the Ohm's law: $V=IR$

The equation(3) becomes: $P=(IR)(I)$

$P=I^{2}R$                                                                               ...........(4)

Put the value of I =V/R in eq.(3):

$P=V(\frac{V}{R} )$

$P=\frac{V^{2}}{R}$                                                                                .............(5)

Therefore, the equation (3), (4) and (5) represent the expression for electric power.