Question

Which of the following terms does not represent electrical power in a circuit?
(a) I2R (b) IR2 (c) VI (d) V2/R

NCERT Class X
Science - Science

Chapter _Electricity

Answer 1

(b) IR²

Because,

(a)P = VI

= IR×I (V=IR)

= I²R

(c) P = VI

(d)P = VI

= V×V/R (I=V/R)

= V²/R

So, (b) I²R not represent power in a circuit

Answer 2

Answer:

I$R^{2}$ term does not represent electrical power in a circuit.

Explanation:

• Power is the rate of electrical energy transfer by an electrical circuit per unit time .
• It is denoted by P and the SI unit is one joule per second or watt.

Formula used for electric power is

P = VI --------(1)

where P = Electric power ,V = Potential difference in the circuit ,I=current

We know from ohms law

V = IR

Substitute V = IR in (1) we get,

P = (IR)I

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

Again From ohm’s law

I = V/R-----------(3)

Substituting equation (3) in equation (1), we get

P = $V^{2}$/R----------(4)

∴The equation (1), (2) and (4) represents the electric power, whereas IR2 does not represent the electric power.

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