# How to find voltage across the resistor?

How to calculate the voltage V0 across the 8ohm resistor? Using mesh analysis I get an answer(120V) which is different from the correct answer.

Left loop, $$4I_1+V_1=120$$ Right loop, $$10I_2+2I_3+V_2=0$$ Outer loop, $$-120+4I_1+8I_3-8I_2=0$$

Solving I get, $$I_3=15A \text{ and }V_0=120V$$

• Is any data given about the transformer? Pleas edit the question to show the steps that you have followed. – AJN Nov 28 '20 at 7:48
• Also, please use MathJax to format equations nicely. Make clear your effort up to point stuck and ask help to get unstuck, not expecting free homework service. – relayman357 Nov 28 '20 at 11:09
• Which 8 ohm resistor? – Hot Licks Nov 28 '20 at 15:52
• @HotLicks The one which is connected to both primary and secondary side. And $V_0$ is the voltage across the resistor. – Rakshith Krish Nov 29 '20 at 12:01

So, draw an arrow going into left side dot and assign it a current variable. Then draw an arrow coming out of the other dot (or in to non-polarity dot side if easier) and assign it the same current variable, but scale it by $$\1/2\$$. Also, assign a voltage variable to one side, scale it and assign with appropriate polarity on the other side as well. Then you can write KVL and KCL equations to solve.
• See if my edit (added circuit with suggested variables) helps. The current up through the bottom right 8Ω resistor (from KCL) is $\frac{i_2}{2}+i_3$. – relayman357 Nov 28 '20 at 14:24