The diameter of the cylinder (D) is 0.01m and the length of the heater (L) = 0.07m. The emissivity of the surface was 0.95 and the Stefan Boltzmann constant was 56.7x10-9
Wm-2K-4. The room temperature was assumed to be 25°C which is 298.15K.
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Human error: we had to wait for the temperature to stabilise and even though we counted 10 seconds on a particular value; if we had waited for longer the values would be different.
Room temperature: the value of 25°C is a general average and not the exact temperature in the room.
Instruments: The instruments have an error. The thermocouple and anemometer will be taking a reading with an error and displaying it on the HT10X which too has an error. The HT10X shows only to two decimal places causing a small error (there are much greater errors in the experiment so this isn’t very significant).
To find the percentage error: (observed value – expected value) / expected value *100
If the experiment was repeated multiple times the results can be averaged. If we had more to time to conduct the experiment we could wait longer for the temperature to stabilise.
The unexpected error for the measured and calculated values are below:...
As the power increases linearly the Qtot also increases but only to a certain point. When the airspeed is greater than 2m/s the Qtot value decreases. The air is cooling the cylinder. The air velocity affects the radiation and convection. The convection decreases as the airspeed increases but radiation increases. The speed of the air increases the radiation due to the passing air and that it is at room temperature (large temperature difference), as soon as the air heats up it has already been replaced with room temperature air. The graph shows the lower the speed of the air the quicker the heater heats up. As the airspeed increases the heater heats up slowly because the air effectively ‘takes’ the...
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