Let's say we have a light bulb of the following rating : 20W, 100V, 20 Ohms.
Let's say that, 20W of power is being supplied to the bulb.
By Ohm's Law current through the bulb will be 100/20 A.
Now if I use the power formula P=VI, I=20/100 A.
Again if I use the heat loss formula P=I^2*R, I will be different.
I want to know where exactly are these formulas used. There must be particular cases where we use them.
Am I interpreting the power formulas wrong?
Now what if the supply is not able to supply the 20W that the load needs. How will it affect the current in the load.