A thermometer can be read to an accuracy of ± 0.5 °C. This thermometer is used

Q#26 (Past Exam Paper – November 2003 Paper 1 Q4 & June 2014 Paper 12 Q5)

A thermometer can be read to an accuracy of ± 0.5 °C. This thermometer is used to measure a temperature rise from 40 °C to 100 °C.

What is the percentage uncertainty in the measurement of the temperature rise?
0.5 %                       0.8 %                       1.3 %                       1.7 %




Solution:
Answer: D.

Initial temperature: T1 = 40 °C
Final temperature: T2 = 100 °C

Temperature rise: T = T2 – T1 = 100 – 40 = 60 °C


The measurement of both the initial and final temperatures have an uncertainty of ± 0.5°C.

ΔT = ΔT2 + ΔT1
ΔT = 0.5 + 0.5 = 1.0 °C


Percentage uncertainty in the measurement of the temperature rise:
%uncertainty in T = [ΔT / T] × 100%
%uncertainty in T = (1/60) × 100% = 1.7%

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