An electric bulb is marked 250W, 230V. (1)How many joules of energy does it consume in one hour? (2)How long would this lamp take to use 1kWh energy when connected to 230volt mains?
Answers
Answered by
9
i) energy consumed in 1 hour, W= P * t, 1 hour = 60s = t; 250W = P. If you fill in the given formula you'd find the energy used in 1hour. the unit of W is in Joules or Wh.
ii) since the supply is the same our P will stay the same and so you can find t by reformulating the previous formula like this t=W/P, 1000Wh = W (changed it to SI unit instead of kWh which is 1000 times greater than Wh the SI unit); 250W = P. fill in the formula and your result will be the time in seconds.
Similar questions