# Thread: Uncertainty calculations

1. ## Uncertainty calculations

Hello,

I'm having problems calculating the uncertainty for Q(energy).

The formula is as follows

Q = VIt

V=voltage
I= current
t=time

say V=10 +-0.05
say I= 5 +-0.005
say t= 120 +-0.005

What would the uncertainty in q be? As I understand it varies for each new reading of t in regards to Q.

2. Originally Posted by Mouseman
Hello,

I'm having problems calculating the uncertainty for Q(energy).

The formula is as follows

Q = VIt

V=voltage
I= current
t=time

say V=10 +-0.05
say I= 5 +-0.005
say t= 120 +-0.005

What would the uncertainty in q be? As I understand it varies for each new reading of t in regards to Q.
$\displaystyle \frac{\delta Q}{Q} = \frac{\delta V}{V} + \frac{\delta I}{I} + \frac{\delta t}{t}$.

Substitute the data and solve for $\displaystyle \delta Q$.