What is the resistance ratio of two bulbs of 100W and 50W at 250V?

This is an interesting and useful question.

With just a bit of algebra and a couple of equations, you can calculate the answer.

The MOST important equation is for Power, P=IV, current times voltage.

You have provided us with a value for the Power of each bulb (100W and 50W) and the voltage of 250V. These are easy numbers. Let's figure out the current through each bulb that produces each power rating.

Current through the 100W bulb =

Current through the 50W bulb =

(Do these numbers make sense? It would seem as though if the voltages are equal then more current would be needed to generate more power. Right?)

Now we have BOTH the current for each bulb AND the voltage for each bulb.

Time for another equation - the definition of resistance, R= V/I, voltage divided by current.

That should wrap things up for you.

(But, WAIT! Let’s actually MEASURE the resistance of each bulb. We’ve gotta find a resistance meter, also called an ohm-meter, to do this. Do NOT be disappointed if your measurements do not agree with your calculations. Life is WY too interesting to get hung up on details like this!)