Potential vs. Current Graph

[Soaring Crane]

1. The problem statement, all variables and given/known data

On my potential vs. current graph for resistors in parallel, the slope of the regression line is 8.94 ohm (V/I = R) for a 10 ohm resistor and a 50 ohm resistor. The theoretical value of R_eq is R_eq = 1/[(1/50 ohm) + (1/10 ohm)] = 8.33 ohm. Upon comparing the two R_eq values, I was wondering why the experimental R_eq value is higher than theoretical value. What sources of error could account for this deviation? (Oh, the regression line's y-intercept value is close to 0; it is 0.004 V.)


2. Relevant equations

See above.

3. The attempt at a solution

See above.

Thanks.

[Hootenanny]

Whats the error on your instruments? Whats the error on your resistors? You answer is with \pm 7%, which is pretty good if your using high school equipment.

[turdferguson]

The other wires in the circuit have a small resistance which is usually assumed to be negligible. This could account for some extra resistance. Also, the resistors are labeled 10 and 50 ohms, but could be higher or lower based on the percentage of error (bottom line on the resistor)