What is the relationship between heat, temperature, and measurements in joules?

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SUMMARY

The relationship between heat, temperature, and measurements in joules is defined through Joule's Law and the specific heat capacity of water. In the discussed experiment, the formula Q = mc(dT) is utilized to calculate heat in joules, where Q represents heat, m is the mass of water, c is the specific heat capacity (4.186 J/g°C), and dT is the temperature change. The experiment involved measuring the temperature change of water heated by an electric circuit, demonstrating the direct correlation between electrical energy and thermal energy. The calculated heat for a 50ml sample of water with a temperature change of 0.03°C resulted in 6.279 joules.

PREREQUISITES
  • Understanding of Joule's Law (W = I²RT)
  • Knowledge of specific heat capacity (4.186 J/g°C for water)
  • Familiarity with basic electrical components (battery, rheostat, ammeter)
  • Ability to perform temperature measurements using a digital thermometer
NEXT STEPS
  • Research the principles of Joule's Law in electrical circuits
  • Learn about specific heat capacity and its applications in thermal energy calculations
  • Explore the effects of varying current on heating in resistive materials
  • Investigate methods for accurately measuring temperature changes in experiments
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Students conducting experiments in physics, educators teaching thermodynamics, and anyone interested in the practical applications of heat transfer and electrical energy conversion.

tomMccune
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Hi everyone,

I have an investigation to carry out for my Junior Certificate in Ireland. What I'm not sure about is the link between heat and temperature. I know that heat is energy, and temperature is the measurement of this energy, but I'm not sure what the link between celsius and joules is.

1. Measure the relation between the current of a circuit and the heating effect produced by that circuit2. Joule's Law - W = (I^2)(R)(t) (I'm sure this comes into it somewhere, my teacher has brought it up.
3. The way that my partner and I have carried out the experiment is:

We would measure 50ml of water and pour it into a polystyrene cup. We would then use a digital thermometer to get a reading of the temperature of the water as a control. This varied each time we got new water and measured it, probably due to weather, humidity etc. We would connect a battery to a rheostat (variable resistor), then to an ammeter, then to a wire coil, which would be submerged in the water in the polystyrene cup, then back to the other battery terminal. So, we have been waiting 8 minutes for the water to heat up, each time with a different current, then measuring the temperature of the water and the increase from the control. How would this be relavent to a measurement in joules (What formula would I use to convert my readings in celsius to Joules?)? I don't get it at all.

Here are our results (A little weird, but we can... edit them, I know they're supposed to be directly related).

table.jpg


Thanks for any help, I hope I've been clear enough.

Tom.
 
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use Q=mc(dT)

Where is the mass of water
c is the specific heat capacity of water
dT is th temperature difference.
 


Thanks. To see if I've got it right:

Q (heat in joules) = m (mass of water, 50ml/cc) x c (heat capacity of water, 4.186j/cm2) x dT (Difference from control, 0.03'C)
= 6.279J

Sorry if I got that completely wrong, I've never done anything like that before.
 
Last edited:


yep, that would be the correct way to calculate it.
 

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