Question

Potentiometer wire of length 1 m is connected in series with
490???? resistance and 2 V battery. If 0.2 mV/cm is the potential
gradient, then resistance of the potentiometer wire is
(a) 4.9 ???? (b) 7.9 ???? (c) 5.9 ???? (d) 6.9 ????

Answer 1

Answer:

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Explanation:

Potential gradient, k=0.2 mV/cm=

10

−2

0.2×10

−3

=0.02 V/m

Potential across potentiometer wire is V

p

=kl=0.02×1=0.02 V

If R be the resistance of potentiometer wire, as per the condition of potnetiometer:

0.02×(R+490)=2R

or 1.98×R=9.8

∴R=4.9 Ω