Which term in the following does not denote the electric power in electric circuit?

Question

Which term in the following does not denote the electric power in electric circuit?

1. A. I²R
2. B. IR² (Correct answer)
3. C. VI
4. D. V²/R

Correct Answer

Option B — IR²

Detailed Solution & Explanation

The correct answer is IR².

Key Points

• IR² does not represent electric power.
• The three valid expressions for electrical power are derived by combining Ohm's Law (V = IR) with the fundamental definition P = VI:
• P = VI — power equals voltage times current.
• P = I²R — substituting V = IR into P = VI.
• P = V²/R — substituting I = V/R into P = VI.
• The expression in option (B) is IR², which incorrectly squares the resistance instead of the current.
• A quick dimensional check confirms this: I²R has units of A² × ohm = watt, whereas IR² gives A × ohm², which is not a unit of power.

Exam Tip

• this question is deliberately designed so that a hurried candidate reads IR² as I²R.
• Always verify such options by dimensional analysis rather than visual recognition.
• The SI unit of power is the watt, where 1 watt = 1 joule per second, and the commercial unit of electrical energy is the kilowatt-hour.

प्रश्न (हिन्दी में)

निम्नलिखित में से कौन–सा पद विद्युत परिपथ में विद्युत शक्ति को निरूपित नहीं करता है?

1. A. I²R
2. B. IR²
3. C. VI
4. D. V²/R