Q E= V·I· t where voltage (V) and current (I) were constant.
To maintain the experiment as fair as possible, the values for voltage and current were maintained constant. Voltage=12V (±0.01V), current= 4A (±0.01A)
Uncertainty (U) of E= U of V + U of I + U of t
U of Q= 0.01+0.01+0.01 ⇨ U of Q= ±0.03J
Q=E therefore Q= V·I·t
Gradient= (24.03744-13.02028)/ (23040-14400) ⇨gradient= 1.28 ·10^-3
Gradient= 1/c ⇨ c= 1/gradient ⇨c=784.2
% error of c= (real value- experimental value)/ (real value) · 100
%error of c= ((878-784.2)/ 878) · 100⇨ % error of c= 10.7%
% uncertainty of c= %u of Q+ %u of m+ %u of T
Average Q= 11520J
%u of Q= (0.03/11520) · 100 ⇨ %u of Q= 2.60 ·10^-4%
Average T = 304.3 k
%u of T= (0.5/304.3) ·100 ⇨ %u of T= 0.164%
%u of m= (0.00001/1.00156) ·100 ⇨ %u of m= 9.98·10^-4%
Therefore the %u of c= 2.60 ·10^-4%+0.164%+9.66·10^-4⇨ %u of c=0.165% (3 s.f.)
Gradient= (21.73227-15.52305)/ (18720-14400) ⇨gradient=1.44·10^-3
Gradient= 1/c ⇨ c= 1/gradient ⇨c=695.7
%e of c= (real value- experimental value)/ (real value) · 100
%e of c= (878-695.7)/ (878) · 100 ⇨%e of c= 20.8%
%u of c= %u of Q+ %u of m+ %u of T
Average Q= 11520J
%u of Q= (0.03/11520) · 100 ⇨ %u of Q= 2.60 ·10^-4%
Average T = 305.5
%u of T= (0.5/305.5) ·100 ⇨ %u of T= 0.164%
%u of m= (0.00001/1.03487) ·100 ⇨ %u of m= 9.66·10^-4%
%u of c= 2.60 ·10^-4%+0.164%+9.66·10^-4%⇨ %u of c=0.164%
Conclusion and evaluation:
Conclusion: differently from what was expected the value for specific heat capacity (c) was closer to the real one when working without the insulator. This happened mainly because when doing the experiment with only the aluminium block, a certain quantity of energy was lost to the surroundings, but when functioning with the insulator, it absorbed a greater quantity of heat. Is true that it stopped some energy to go to the environment, but in the other hand it took more heat than the one that was lost to the surroundings when using only the aluminium block. This can be proven with the value for the percentage error of the specific heat capacity, which was 10.7%, compared to the 20.8% of the aluminium block with the insulator, meaning that the aluminium block by itself had a closer value to the real specific heat capacity. But equally neither of them was very accurate, meaning that the system had a systematic error. In the other hand both of the values for specific heat capacity had a very low percentage uncertainty, 0.165% for the aluminium and 0.164% for the aluminium with the insulator. Therefore the experiment was precise, so there was a very low random error.
Limitations and improvements:
