# PhysicsKirchoff's question

#### Cbarker1

##### Active member
Dear Everybody,

I have difficulties how to use the loop rule and junction rule for the diagram below.

I need to find R4 and V1 and V2 in this question.

Work:

J1: $I_1=I_2+I_3$
J2:?
J3:?
J4:?

Thanks,
Cbarker1

L1:?

#### castor28

##### Well-known member
MHB Math Scholar
Hi Cbarker1 ,

The top loop gives you the equation:
$$V_1 = I_1R_1 + I_3R_3 + I_2 R_2$$
This will give you $V_1$.The bottom right loop gives:
$$V_2 = -I_3R_3 + I_5R_5$$
This will give you $V_2$. The bottom left loop gives:
$$V_2 = I_2R_2 - I_4R_4$$
and this will give you $R_4$.