Finding the missing Resistor of a circuit

[deniedyou]

Hi i have two questions that i really need help with

i have a series diagram which is like this:

Vs = 24 V
R1 = 2 ohm
R2 = 4 ohm
R3 power = 24 W
what is the value of R3 resistor?


please if u can explain in details step by step it would be helpful thank you


2nd question :

R1 = 2ohm
R2 = 4 ohm
R3 power = 24 W
Is = 19 A
Vs = not given

what is the value of R3 resistor?


thank you

 

[davenn]

hi, welcome to the forums

ok here's a great www site for working out voltages across resistors in series
you can use examples there to work out unknown battery voltage current in a cct etc

have a read and apply the formulas to your values and see how you go then ask a few more questions here on anything yoou dont understand

http://www.tpub.com/neets/book1/chapter3/1-12.htm

cheers
Dave

 

[(*steve*)]

I would try the second one first. It seems to b a simple application of the appropriate formula that you should have on the tip of your tongue (involving power, current and resistance).

 

[lexroxas]

All you need to find the answers to your question is to study "Ohm's Law". It's all in there.