Question

An Electric bulb is marked 100W, 230V. What how long would this lamp take to consume one unit of electricity?

Answer 1

If the lamp of 100W 230V be connected to the prescribed voltage of 230V then it consumes 100J electrical energy in 1 s.So in 1hr or 3600s it consumes 360000J.

1 unit or 1kWh energy means 1000×3600=3600000J of electrical energy.

Hence time required for consumption of 1 unit of electricity by the given bulb will be 10hrs

Answer 2

Energy consumed in kwh = (w x time in hour)/1000

= (100 x t(in hr)/1000

If energy consumed in 1kwh, then 1 = (100 x t)/1000

time required for consuming 1kwh, t = 10 hour.