Current Electricity Charging Discharging Of Capacitors Question 108
Question: The thermo e.m.f. of a thermo-couple is $ 25\mu V{{/}^{o}}C $ at room temperature. A galvanometer of 40 ohm resistance, capable of detecting current as low as $ {{10}^{-5}}A, $ is connected with the thermocouple. The smallest temperature difference that can be detected by this system is
[AIEEE 2003]
Options:
A) $ 20^{o}C $
B) $ 16^{o}C $
C) $ 12^{o}C $
D) $ 8^{o}C $
Show Answer
Answer:
Correct Answer: B
Solution:
$ e=iR $
Therefore $ 25\times {{10}^{-6}}\times \Delta \theta ={{10}^{-5}}\times 40 $
$ \Delta \theta =\frac{40\times {{10}^{-5}}}{25\times {{10}^{-6}}}=\frac{400}{25}=16{}^\circ C $
BETA
