Heating Effect of a Electrical Current

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Isaac Wong 10H                                                                                                          

Science Investigation (Physics) -- Heating Effect of a Electrical Current


I will investigate the relationship between the current pass through water and rise the temperature of the water. I will control variables including: the mass of water in the beaker, the voltage, whether the beaker is insulated or not, the time duration used to obtain the results. I will change the values of the resistor. The initial value of the resistor is 3 Ω, I will start off from 3 Ω and the final value I will take is 10 Ω. I will do increments of 1 Ω, therefore I will be able to obtain 7 results and it will be sufficient for me to prove my prediction. Instead of using practical apparatus, I used a computer simulation to investigate the relationship between electrical current and the raise in temperature. The only tool we need for this experiment is that computer simulation. 

Fair Test:

Variables that will affect the current, which affects the temperature: voltage, resistance, mass of water, time

I will keep voltage, mass of water and time the same so then I will only be varying one factor that affects current/temperature.

Values I will keep constant: Voltage – 6V, Mass of Water – 30g, Time – 15 minutes.

Variables I will change: Resistance – from 3 ohms to 10 ohms – range of results.

Why voltage should be kept constant: This is because as voltage increases, current also increases. The equation for voltage is V = iR, so if R is kept constant, V increases will cause i (current) increase.

Why mass of water should be kept constant: Water has a high specific heat index. This means that water can absorb a lot of heat before it begins to get hot. So the less water, the temperature will increase more and vice versa. Therefore water is a factor for temperature change so must be kept constant for a fair test.

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Why time should be kept constant: This is because if there is more time for the heater to convert the electrical energy to heat energy, the water will heat up more. This means if I take a result using the same resistance, voltage and mass of water using the time 1 minute, the temperature will be lower than another result I take using the time 30 minutes.

This explains how voltage, mass of water, time affects the temperature. I must keep them constant and only change one variable (resistance) to keep this experiment a fair test.

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