Three infinitely long parallel straight current carrying wires A, B and C are kept at equal distance from each other as shown in the figure. The wire C experiences net force F .The net force on wire C, when the current in wire A is reversed will be

(i) Zero

(ii) \( \dfrac{F}{2}\)

(iii) F

(iv) 2F

Asked by Abhisek | 2 years ago |  100

1 Answer

Solution :-

Right answer is (i) Zero


Let F1 is force per unit, length between A & C

\( F_1=\dfrac{\mu_0}{4\pi}\dfrac{2I\times I}{2r}\)

And F2 is force per unit, length between B & C

\( F_2= \dfrac{\mu_0}{4\pi}\dfrac{I\times I}{2r}\)

Now net force on ‘C’ is per unit length

\(F_1+ F_2= \dfrac{2\mu_0}{4\pi}\dfrac{I^2}{r}=F\)

\( F_1'\) = Repulsive force between A & C

\( \dfrac{\mu_0}{4\pi}\dfrac{2I^2}{2r}\)

\( F_2' = F_2 =\) A reactive force between B & C

Net force on \( 'C'\;F_1'-F_2'=0\)

\( F_1'=F_2'= \dfrac{\mu_0}{4\pi}\dfrac{2I^2}{2r}\) 

Net Force on ‘C’ is zero.

Answered by Pragya Singh | 2 years ago

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