AIPMT | 2015Current Electricity and Electrical InstrumentEasy
Question
A potentiometer wire has length 4 m and resistance 8Ω The resistance that must be connected in series with the wire and an accumulator of e.m.f. 2V, so as to get a potential gradient 1 mV per cm on the wire is :
Options
A.40 Ω
B.44 Ω
C.48 Ω
D.32 Ω
Solution
Potential gradient = 
= 10-3 V/cm = 10-1 V/m
Let the resistance to be connected is R then
I =
Potential drop across the potentiometer wire
Potential gradient =
V/m
=
= 0.1
⇒ R = 32Ω
Hence option (4)
= 10-3 V/cm = 10-1 V/mLet the resistance to be connected is R then
I =
Potential drop across the potentiometer wire
Potential gradient =
V/m=
= 0.1⇒ R = 32Ω
Hence option (4)
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