Determining the specific heat capacity of water

AI Thread Summary
The discussion focuses on determining the specific heat capacity of water using a calorimeter, voltmeter, and ammeter, with concerns about significant random errors in the voltage and current readings. The user recorded fluctuating measurements every minute, leading to a calculated specific heat capacity value of 3.95 ± 3.45% J g-1 K-1. Suggestions were made to plot the readings over time to assess the nature of the errors and to consider factors such as stirring the water and the precision of the measuring instruments. The importance of significant digits in the measurements was also highlighted. Overall, the conversation emphasizes the need for careful analysis of experimental data to identify potential sources of error.
VegemiteJuice
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Homework Statement


Hi,
I have an assignment to determine the specific heat capacity of water using a calorimeter, voltmeter and ammeter, where we connected the calorimeter to a 10V power pack and measured the temp of the water and the readings on the voltmeter and ammeter every minute. I ended up having a huge random error for the voltmeter and ammeter (3.01%) - any idea why this is?
Also what should I talk about in my discussion?

Homework Equations


To calculate the specific heat capacity I used
PΔt = mc(water)ΔT + mc(calorimeter)ΔT
and I got a value of 3.95 +- 3.45% J g-1 K-1
 
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What do you mean by a "huge random error for the voltmeter and ammeter"? Were the readings fluctuating up and down? Changed gradually over time?
 
Hi Juice, :welcome:

So you have three series of T, I and V as a function of time. It would be logical to plot them as a function of time to see if the errors are really random, or that there is more going on.
 
CWatters said:
What do you mean by a "huge random error for the voltmeter and ammeter"? Were the readings fluctuating up and down? Changed gradually over time?
We wrote down the measurements displayed on the ammeter and voltmeter every minute, until the water had increased by over 20K (it took 5 minutes). The readings on each fluctuated every time, and the random errors were 0.11A and 0.1V, which ended up being quite a large % error.
 
How do you know they were errors ?
 
BvU said:
Hi Juice, :welcome:

So you have three series of T, I and V as a function of time. It would be logical to plot them as a function of time to see if the errors are really random, or that there is more going on.
Alright, I'll try that.
Thank you BvU!
 
did you stir the water during the experiment?
 
+1 to the questions above.

Also..

How many digits could the meters display? 10.1V is three significant digits. Could it display 10.05V or is 10.1V the nearest it can get?
What was a typical current? Something like 3.11A is also three significant digits.
 

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