Question

how much energy is used by a 100w bulb in 3.5 hours

Answer 1

Heya!

Here,

Power (P) = 100W

Time(t) = 3.5 hours = 12600s

Energy = ?

Since, Power = Energy/Time or P = e/t,

e = P*t = 100*12600 = 1260000 Joules or 1260 kJ or 1.26 MJ

Hope it helps!

Answer 2

We know that,

Energy= Power x Time

           = 100 W x 3.5 hrs

           = 0.1 KW x 3.5 hrs

           =  0.35 Joules