dc series circuit problem

Thread Starter

pidge

Joined Apr 26, 2010
1
i have 3 resistors in a 329VDC circuit series R1=9V R2=25ohms R3=15ohms how can i find out the ohms value for R1 or what i'm thinking is it's a trick qu. and i need more values
 

TheWeasel

Joined Aug 28, 2009
4
beenthere's right, there's no trick, you have all you need, and it can be worked out as follows;

The volts drop given across R1 is 9v which leaves the remaining 320v to be dropped across R2 + R3 (40 ohms).
I=V/R so 320/40 gives 8 Amps.

Knowing the current now permits calculation of the value of R1 needed to drop 9v at 8A ;
R= V/I or 9/8 which makes R1 = 1.125 ohm

As a double check in the complete circuit;
V/R = I or 329V/41.125R = 8A......so it all fits together.
 
Last edited:

beenthere

Joined Apr 20, 2004
15,819
To TheWeasel - it might be more instructive to get the OP to make some of the calculations and see some of the relationships himself. More learning goes on that way.
 

kingdano

Joined Apr 14, 2010
377
i agree with beenthere - but for me it was always helpful to see an example worked through once in a while.

so kudos to both of you for the helpful posts to the EIT.
 
Top