Is one joule per second equivalent to one watt ?

Yes, one joule per second is equivalent to one watt. Here's the detailed explanation:
Definition of Power:
Power is the rate at which work is done or energy is transferred. It is mathematically expressed as:
P=WtP = \frac{W}{t}
Where:
• PP is power.
• WW is the work done or energy transferred (in joules, JJ).
• tt is the time (in seconds, ss).
Definition of the Watt:
The watt (WW) is the SI unit of power and is defined as:
1 watt=1 joule per second1 \, \text{watt} = 1 \, \text{joule per second}
This means if a device transfers or uses 1 joule of energy in 1 second, its power output is 1 watt.
Verification:
Using the formula for power:
P=WtP = \frac{W}{t}
If W=1 jouleW = 1 \, \text{joule} and t=1 secondt = 1 \, \text{second}:
P=1 joule1 second=1 wattP = \frac{1 \, \text{joule}}{1 \, \text{second}} = 1 \, \text{watt}
Conclusion:
Yes, 1 joule per second is exactly equal to 1 watt. This is the fundamental definition of the watt in the International System of Units (SI).