How to calculate thevenin's voltage?

Nov 2018
5
0
CircuitProb.png

How do i calculate the potential difference between Va and Vb?
 
Apr 2017
523
126
First just consider the right side of the circuit ... what is the voltage across the 6 Ohm resistor (from the 18V battery) ...

Once you have that voltage you can add or subtract (depending on polarity) from the 72 V to get the answer you require.
 
Nov 2018
5
0
i understand that Va = 72 V. But Vb is supposed to be -12 V and the potential difference across Va and Vb is supposed to be 84 V. I want to know how Vb is -12 V
 
Apr 2017
523
126
The two batteries are connected in such a way that the +ve side of one connects to the -ve side of the other this means the voltages add .