Direct energy is applied to the substance using an electrical current. For a liquid, this is in the form of a heating element being placed in the liquid, and for a solid, holes are cut in the block for an electric heater and thermometer. The total amount of energy supplied by such an electric heater is VIt, where V = the potential difference across the heater, I = the current running through it and t = the time the heater is on for (in seconds). Therefore, VIt = m x C x delta-T .
Variables:
According to the specific heat capacity the mass of a substance and the time in seconds will affect the temperature rise. However I will be changing the lenth of the time for which the cylinder is heated for instead of energy because it is much easier to calculate.
Prediction:
Method:
Apparatus: Aluminium cylinder
Immersion heater
Power pack
Some leads
Stopwatch
-Clear your work space to avoid accidents
-Gather all the equipment you will use
-Switch on the power pack and measure the voltage output with a voltmeter and record it to get more accurate results
-Turn off the power pack then plug it to an ammeter and then from the ammeter connect it to an immersion heater
-After this is done connect the voltmeter in parallel to the immersion heater (across the immersion heater)
-Using a stopwatch set it to timer mode
-Record the starting temperature
-Once this is done switch on the power pack at the same time start the timer
-Record the results down (voltage, current temperature) every two minutes
-Stop the experiment after twenty minutes (or after a reasonable amount of time)
-You may want to repeat the experiment a few times to get even more accurate results
Definitions
Ammeter – This is a device that measures the current of electrons in Amps. It has to be placed in series on the circuit.
Voltmeter – This is a device for measuring the potential difference of the electrons in the circuit. They are measured in Volts. It is placed in parallel.
Circuit Diagram:
Diagram:
Preliminary Results:
Final Results:
Conclusion:
The final results allow me to see many different patterns. On of the first things I noticed was how the extra amount of time made the temperature rise increase significantly. However when it reached a certain temperature
Evaluation:
Unfortunately the results did not match those in my conclusion, but now I have confirmed that after the temperature reaches a certain level the pattern stops. I have tried to identify which factors affected my experiment. One of the factors was when weighing the 1Kg aluminium block was that when I weighed it on the scale it was 999.4g. I used 1 kilogram, as the weight in the calculations so therefore would have given me slightly inaccurate results.
There could have been other errors such as the stopwatch. The stopwatch has inaccuracy of 0.5%, which would also slightly affect the outcome in the final results.
I cannot blame the equipment totally because most of the errors would have been carried out by humans.
Diren Pillaysamoo 10V
