Question 372: Current Electricity

Question

The thermo $$e.m.f.$$ of a thermo -couple is $$25$$ $$\mu V/{}^ \circ C$$ at room temperature. A galvanometer of $$40$$ $$ohm$$ resistance, capable of detecting current as low as $${10^{ - 5}}\,A,$$ is connected with the thermo couple. The smallest temperature difference that can be detected by this system is

Accepted Answer

Let $$	heta $$ be the smallest temperature difference that can be detected by the thermocouple, then
$$I 	imes R = \left( {25 	imes {{10}^{ - 6}}} ight)	heta $$
where $${m I}$$ is the smallest current which can be detected by the galvanometer of resistance $$R.$$
$$	herefore$$ $${10^{ - 5}} 	imes 40 = 25 	imes {10^{ - 6}} 	imes 	heta $$
$$	herefore$$ $$	heta  = {16^ \circ }C.$$

Answer

$${16^0}C$$

Answer

$${12^0}C$$

Answer

$${8^0}C$$

Answer

$${20^0}C$$

Current Electricity

The thermo $e.m.f. of a thermo -couple is 25 \mu V/{}^ \circ C at room temperature. A galvanometer of 40 ohm resistance, capable of detecting current as low as {10^{ - 5}}\,A,$ is connected with the thermo couple. The smallest temperature difference that can be detected by this system is

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