An Investigation Into The Factors Affecting The Temperature Rise of Water Heated Electronically

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Mihir Desai

Physics Coursework

An Investigation Into The Factors Affecting The Temperature Rise of Water Heated Electronically

Plan

In this experiment I am trying to find out, how different factors affect the temperature rise when heated electronically.

Variables

        In this experiment the key variables I am considering are:

  • Time (t)(s)
  • Power (IV)(W)
  • Mass of water (M) (g)
  • Change of temperature (∆t) (oC)

The variables that are fixed must remain the same in order to attain an accurate conclusion, if they were not it would make the experiment void. Any 2 variables can be varied but the other 2 must be held fixed. I have a choice in what factors will be fixed or varied either:

  1. Power and time are fixed, whilst mass and change it temperature remain varied. E.g. I would put a fixed power for a fixed time and see how the change in temperature relates experimentally to the mass of the water.
  2. Mass and time are fixed, whilst power and change in temperature vary. E.g. I would see how the power input and change in temperature relate to each other.
  3. Power and mass are fixed, whilst time and change in temperature vary. E.g. I would have a fixed power input and mass, in order to see how both factors relate to one another.

Preliminary experiment

In my preliminary experiment, I have chosen to investigate two different factors; these are keeping the mass and time fixed, and keeping the power and mass fixed. In the preliminary experiment I am aiming to find out the most suitable independent factors to use in the actual experiment. As well as this I am trying to find out the most suitable volumes of water to use, so the experiment does not take too long or too slow to make an accurate evaluation.

Apparatus

  • Beaker
  • A polystyrene cup
  • Water
  • A heater
  • A thermometer
  • A power supply
  • An ammeter
  • A voltmeter
  • Electronic weighing scales
  • Stopwatch
  • Wires

Method

        In the first experiment I used time and power as the independent variables while keeping change in temperature as the dependant variable.  So in this way I am keeping the mass and power fixed while changing the time. Firstly I created the circuit using the connecting wires, power pack, voltmeter, and ammeter.

        After connecting the circuit, I filled the polystyrene cup with 68 grams of water, and then I put the cup into the beaker and put the heater into the water. Then I took the starting temperature of the water, and placed the thermometer and placed it in the water.  I then switched on the power at 3 volts though I decided this was taking too long; so I turned the power to 5 volts, which was more suitable.  After every 30 seconds the temperature was recorded.

 A Diagram showing the set up of the Apparatus

        The second preliminary experiment was conducted in the same way, though here the power was the variable, and the change in temperature was named as the dependant variable. I fixed the mass of the water at 20 grams and the time for 4 minutes; I felt this was appropriate as if I used 1 volt of power it would take a long time for a large amount of water to be heated.

Results

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First experiment

Second Experiment

Conclusion

        After looking at the result I can see that the first experiment the longer I left the heater in the water, the hotter the water became. In the second experiment I saw that using more power there was a larger change in temperature.

        So after looking at my preliminary results I have decided that the independent factors that I will investigate in this experiment will be time and power, so therefore I will fix the mass of the water and the power. In the real experiment I will record every result ...

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