Question

What is Joule/second

• A. Dyne
• B. Watt
• C. Newton
• D. Pascal

Hint:

Always analyze unit ratios:
\[ \frac{\text{Energy}}{\text{Time}} = \text{Power} \implies \frac{\text{Joule}}{\text{Second}} = \text{Watt} \]
This unit analysis helps prevent errors.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Power is defined as the rate at which work is done or energy is transferred.
The SI unit of power is defined by the ratio of the SI unit of work/energy to the SI unit of time.

Step 2: Detailed Explanation:
The formula for power (\(P\)) is:
\[ P = \frac{\text{Work Done }(W)}{\text{Time }(t)} \]
In the International System of Units (SI):
- The unit of work or energy is the Joule (\(\text{J}\)).
- The unit of time is the second (\(\text{s}\)).
Thus, the unit of power is:
\[ 1 \text{ Unit of Power} = 1 \text{ Joule/second (J/s)} \]
This combined unit is named the Watt (\(\text{W}\)) in honor of James Watt:
\[ 1 \text{ Watt} = 1 \text{ J/s} \]
Let us identify the other options:
- Dyne: CGS unit of force.
- Newton: SI unit of force.
- Pascal: SI unit of pressure (\(\text{N/m}^2\)).
Therefore, Joule/second corresponds to the Watt.

Step 3: Final Answer:
Joule/second is equivalent to the Watt.