Originally Posted by **Jeff18** I need help to solve this problem. Can anyone help me to solve this exercise? I can not really solve it. The source is Halliday.
Thanks in advance.
Prove that if a resistor of resistance r is inserted between points $a$ and $b$ of Figure 27.39 (attached figure), the current throug it is given by
$i = \frac{E(R_s - R_x)}{(R+2r)(R_s+R_x)+2R_sR_x}$
where $E$ is e.m.f. of the ideal battery and $R=R_1=R_2$
Assume that $R_0=0$ |

The rules of this forum only allow us to help you once you've shown what you've done so far or to give you a nudge if you're unable to get anywhere at all. The later seems to be the case here so here's a hint: Draw the circuit another way, in a way that makes it look very easy to work with. Once you've done that you can use what you already know, i.e. expressions for the resistance of resistors in and parallel and in series, to solve the problem. Take it step by step.