The S.I unit of power is

Analyze the question: You are asked for the S.I. unit of power.

Explain the concept: Power is the rate at which work is done or energy is transferred:

Power = Work done ÷ Time

Show the solution:

• Work done is measured in joules (J)
• Time is measured in seconds (s)
• So, Power = J ÷ s = J/s, and 1 J/s is given the special name watt (W)

Check the other options:

• A. N (newton) is the unit of force
• B. Pa (pascal) is the unit of pressure (N/m²)
• C. W (watt) is the unit of power
• D. J (joule) is the unit of work and energy

Answer: The correct option is C. W.

Tip: Remember the pairing "Watt for Work rate", meaning power is how fast work is done. Also, don't confuse W (the unit, watt) with W (the symbol for work). In exams, always match each quantity to its unit:

• Force: N
• Pressure: Pa
• Energy/Work: J
• Power: W