# Resistor and power output varying with a distance x

1. May 2, 2013

### Jonnyto

1. The problem statement, all variables and given/known data
Figure 29 shows a battery connected across a uniform resistor R0. A sliding contact can move across the resistor from x=0 at the left to x=10 cm at the right. Find an expression for the power dissipated in the resistor R as a function of x. Plot the function for ℰ=50 V, R=2000Ω , and R0=100Ω

2. Relevant equations
P=$\frac{V2}{R}$

3. The attempt at a solution
I have no clue at all on how to solve this problem. I think that it might have to do with how resistors are adding up in parallel. I really can't see which one is in parallel. I don't see how to determine the resistance with the varying x.

2. May 2, 2013

### voko

This circuit is equivalent to three resistors: Rl, Rr, and R. Rl and Rr are the left and right, correspondingly, parts of Ro; their values depend on x. Solve for voltage at R and current through it.

3. May 2, 2013

### SammyS

Staff Emeritus
It's helpful to post a full size image if it's not too large.

4. May 2, 2013

### arifz2303

may be this be help..
$R_{total}=(R // R_{p}) + R_{s})$

just as Voko said #2

5. May 13, 2013

Complex