Step 1: Understanding the Concept:
Power is a physical quantity that measures the rate at which work is performed or energy is converted from one form to another.
If two machines do the same amount of work, the one that completes it in less time is said to be more powerful.
In electrical terms, power is the product of voltage and current.
Key Formula or Approach:
The basic definition of power (\( P \)) is:
\[ P = \frac{\text{Work Done}}{\text{Time Taken}} = \frac{W}{t} \]
Step 2: Detailed Explanation:
The standard International System of Units (SI) unit for work is the Joule (J) and for time is the second (s).
Thus, the unit for power is Joules per second (\( J/s \)).
This unit is named the "Watt" (symbol: W) in honor of the Scottish engineer James Watt, whose improvements to the steam engine were fundamental to the Industrial Revolution.
One Watt is defined as the power developed when one Joule of work is done in one second.
Let's analyze the other options to understand why they are incorrect:
- (A) Pascal (Pa): This is the SI unit of Pressure. It is defined as one Newton of force applied over an area of one square meter (\( 1\text{ Pa} = 1\text{ N/m}^2 \)).
- (C) Dyne: This is a unit of Force in the CGS (centimetre-gram-second) system. It is much smaller than a Newton (\( 1\text{ Newton} = 10^5\text{ dynes} \)).
- (D) Volt (V): This is the SI unit of Electric Potential or electromotive force. It measures the energy per unit charge.
Since Watt is the only unit listed that represents a "rate of doing work," it is the correct answer.
Step 3: Final Answer:
Among the given options, the Watt is the standard SI unit of power.