Question

How much energy is used when the incandescent bulb is left on for 12 hours

Answer 1

You haven't told us the "wattage" rating of the bulb.  We'll just have to call it ' W ' .

The bulb uses energy at the rate of W watts, or 0.001W kilowatts.

In 12 hours, it uses 0.012W kilowatt-hours of energy.

= = = = =

W watts = W Joules/second

1 hour = 3600 seconds

12 hours = (12 x 3600) seconds

Energy = (W Joule/sec) x (12 x 3600 sec)

Energy =  43,200W Joules