Calculate the length of a constantan wire of cross- sectional area 4 π x 10-8m2 and resistivity 1.1 x 10-6 Ω m required to construct a standard resistor of resistance 21 Ω. [Take π = 22/7]
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Correct Answer: Option B
Explanation:
R = PL/A => L =
RA/P
=
21 x 4π x 108/1.1 x 10-6
= 2.40
R = PL/A => L =
RA/P
=
21 x 4π x 108/1.1 x 10-6
= 2.40