# How do you 'compound errors'?

Thread starter 8 years ago
#1
In a capacitors experiment for A2 we have to compound our errors as part of the coursework, and I'm not sure how to do that. We'll be using a pretty standard circuit for charging and discharging, so, an emf in series with a capacitor, a capacitor in series with an ammeter and in parallel with a voltmeter, and a switch to go from charging by the emf, to discharging across the circuit ( the circuit contains a resistor in parallel too ) I also think we'll be using a stopwatch. I know that generally the capacitor and resistor are the main sources of error and have their percentage errors on them, but I don't know how to compound all of the errors of all of the things. Help please!
0
8 years ago
#2
The method for combine uncertainties depends on the formula you'll be using.

I think doing a search for "percentage uncertainty" would be fruitful as this is a very frequently asked question with a lot of good answers already here.
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8 years ago
#3
(Original post by Jessticcles)
In a capacitors experiment for A2 we have to compound our errors as part of the coursework, and I'm not sure how to do that. We'll be using a pretty standard circuit for charging and discharging, so, an emf in series with a capacitor, a capacitor in series with an ammeter and in parallel with a voltmeter, and a switch to go from charging by the emf, to discharging across the circuit ( the circuit contains a resistor in parallel too ) I also think we'll be using a stopwatch. I know that generally the capacitor and resistor are the main sources of error and have their percentage errors on them, but I don't know how to compound all of the errors of all of the things. Help please!
You look at the formula that you are using and you add together all the percentage uncertainties multiplied by the power that is in the equation(ignore negative signs in the power) and constants like pi if A=pi*B^2C/(X^3Y) then the total percentage uncertainty in A would be the percentage uncertainty in B multiplied by 2 + the percentage uncertainty of C +the percentage uncertainty of X multiplied by 3+ the percentage uncertainty of Y.
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