Question

1. The lamp in your room is marked (100

W, 220 V). What do these readings mean?
Calculate, in J and in kWh, the electric ener-
gy consumed for 5 hours of lighting. Deduce
the monthly cost if the price of one kWh is
55 L.L.

Answer 1

See the answers below

Step-by-step explanation:

The data of 100W means power, and the other data of 220V means voltage, that is to say that bulb serves to work at a voltage of 220V100W datum means power.

J means work that is given in Joules [J], we must remember that power is defined as the relationship between work at a certain time, therefore we can determine work by means of the following expression.

`P=W/t\\`

where:

P = power [Watt]

W = work [J]

t = time [s]

`W=P*t\\W=100*5[hr]*[(3600s)/(1hr) ]\\W=1800000[J] = 1.8[MJ]`

Now the electric cost.

`0.1[kW]*5[hr]*55(LL)/(1kwhr) =27.5[LL]`