# Finding the missing Resistor of a circuit

Discussion in 'Electronics Homework Help' started by deniedyou, Mar 22, 2011.

1. ### deniedyou

1
0
Mar 22, 2011
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

2. ### davennModerator

13,984
2,015
Sep 5, 2009
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

3. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,505
2,849
Jan 21, 2010
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).

4. ### lexroxas

37
0
Apr 15, 2011
All you need to find the answers to your question is to study "Ohm's Law". It's all in there.