Does the volume of water affect efficiency of heater?

[Daniel Manetas]

Ok, so i did a physics experiment a few days ago and now i have to do a write up. The question is does the volume of water in the calorimeter affect the efficiency of the immersion heater? Could someone pls explain to me what happens & y? My results showed that as you increase the volume, the efficiency decreases. Anyone know why that happened?

 

[Andrew Mason]

Welcome to PF Daniel!

You will have to provide some details of your experiment. The first step in getting help is providing a clear statement of the problem.

AM

 

[vanhees71]

It's not only the first step in getting help, it's also the indispensable first step to find an answer!

 

[Daniel Manetas]

Ok, so i used the formula q=mcT to work out the energy output and P=VI then E=PxT to work out the energy input, then divide these by each other to work out the efficiency. Does anyone know why i got the results i did? Like the scientific reasoning behind it.

 

[NTL2009]

Have you considered what changes when you increase the volume of water? There is more surface area, so there could be more heat loss. Could that account for it.?

 

[Andrew Mason]

You will have to explain:
1. How you conducted the experiment I.e. the setup, what you did and what you measured
2. Your result, and
3. How you analysed the results

Just a few quick comments:

You seem to be using T for two different quantities: 1. change in temperature and 2. Time.

It is difficult to understand how an electric heating element would be much less than 100% efficient in converting electrical energy into heat.

AM

 

[CWatters]

+1

Immersion heaters are generally 100% efficient in that all the heat they dissipate ends up in the water. Some might be lost by thermal conduction down the wires but that's usually small enough to be negligible.

I agree with ntl2009 in that the losses might affect the results. Normally you have to calibrate the calorimeter, perhaps by measuring how much power is needed to maintain a steady water temperature.

 

[CWatters]

Did the water boil?