
To solve for VB - VA in the given circuit, we analyze the circuit using Ohm's Law and the principles of series circuits.
The circuit consists of a 15 V battery and two resistors, 1 Ω and 2 Ω, in series.
The calculated value is -10 V, which falls within the expected range of 10 to 10 V.
Thus, VB - VA = -10 V.
Resistance of each side is $R$. Find equivalent resistance between two opposite points as shown in the figure. 