Si unit of power is watt which is equal to joulepersec
As power = energy /time

The SI unit of power is J/s (joules per second).

Explanation:
Power is defined as the rate at which work is done or energy is transferred or converted. It is a measure of how quickly energy is being used or produced. The SI unit of power is derived from the base units of energy and time.

Power can be calculated using the formula:

Power (P) = Energy (E) / Time (t)

Where energy is measured in joules (J) and time is measured in seconds (s). When we substitute these units into the formula, we get:

Power (P) = Joules (J) / Seconds (s)

This is equivalent to J/s, which is the SI unit of power.

- The option a) kW (kilo-watt) is incorrect because kilowatt is a unit of power, but it is a larger unit than the SI unit. 1 kilowatt is equal to 1000 watts.
- The option c) Ws (watt-second) is incorrect because watt-second is a unit of energy, not power. It represents the amount of energy transferred in one second at a rate of one watt.
- The option d) J/h (joules per hour) is incorrect because joules per hour is a unit of energy, not power. It represents the amount of energy transferred in one hour.
- The correct option b) J/s (joules per second) is the SI unit of power and is derived from the base units of energy and time.

In conclusion, the SI unit of power is J/s (joules per second), which represents the rate at which energy is transferred or converted.