I am not able to solve this question , I initially thought that in order to find the current of this series circuit it would be Vtotal / RTotal , however I am not getting the correct answer with this method. There must be another factor I'm not aware of when it comes to dealing with 2 voltage sources. Can anyone shed any light on why I'm not getting the correct answer ? enter image description here

  • \$\begingroup\$ Please show your work. We won't do your homework for you, but if you show what you did we can help show you where you went wrong. \$\endgroup\$
    – The Photon
    Nov 3, 2015 at 0:03
  • \$\begingroup\$ VTotal / Rtotal is the right approach. If you got the wrong answer it must be because of things that you haven't yet mentioned. \$\endgroup\$ Nov 3, 2015 at 0:48
  • \$\begingroup\$ Remember that the voltage sources are not summing. Think Thevenin equivalent! \$\endgroup\$
    – Josh Jobin
    Nov 3, 2015 at 1:04
  • \$\begingroup\$ I=2.5A and V=17.5V \$\endgroup\$ Nov 3, 2015 at 4:15

1 Answer 1


recognize that the two voltage sources are not acting in the same direction.so you need find the resultant voltage in that circuit which is 50v-12.5v=37.5V and use the formula you wrote above to find I=37.5v/Rtotal = 37.5/15 = 2.5A. The voltage across the 7 ohm resistor is gotten by applying ohms law: v=IR = (2.5)(7)= 17.5v


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