# Use Superposition to solve for Voltage and a Current. NEED HELP!!!!

#### Green024

Joined Feb 25, 2009
3

#### Green024

Joined Feb 25, 2009
3
i just dont get what voltages to put down for the voltage sources, your link helps... but the problem from just the way its written confuses me.

#### vvkannan

Joined Aug 9, 2008
138
Hi green024,
For the first question draw the voltage sources first (1st source with negative terminal at the top and 2v battery as the second source)

Now short circuit 2v battery and find the current through 30 ohm resistor (use ohms law first and then current division rule)

Now short circuit the -5v battery and find the current through 30 ohm in a similar manner from which you can find the voltage across that resistor(be careful with the sign)

for question 2 short the Ev battery and find the current through the 2 ohm.let this be x ampere.
Now short 37 volt battery and we know the current through 2 ohm (i.e)
5-x
Now find the total current from E battery.(current division rule gives total current = (5-x) x (9/4).
find the equivalent resistance seen by the source {5||4 combination series with 2.5}and multiply by the value of current to get the supply E.
Hope this helps