DC Circuits

0. Uncertainty of DMM

If the uncertainty in the reference manual gives an equation of

m% + n dgt,

it means that, say your measured value is x = abc.defg, then

δx = m%*x + n*0.0001.

1. Kirchhoff's Laws

If z = x + y, then

.

2. Ohm's Law: V = I R

Rewrite (Linearize)

as

.

Given U and I are measurable, their associated uncertainties are

,

and

.

For a resistor, the intercept d = ln(a) = ln(R), which makes

,

and

.

We are testing b = 1 for the resistor, so don't assume the relationship is linear.

If b ≠ 1, we can't say that it follows Ohm's law (V = I R).