A conductor PQ of length b carries a current i2 is placed perpendicular to a long conductor XY carrying a current i1 as shown in figure. The magnitude and direction of the magnetic force acting on PQ is
Both the conductors are in xy−plane.
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Solution
Let us consider, a current element of size dx on PQ at a distance x from the current carrying conductor PQ as shown in figure.
Force on the current element,
⇒−→dF=i2(−→dx×→B)
=i2[dx^i×μ0i12πx(−^k)][B:is the field due to XY]
=μ0i1i2dx2πx^j
Integrating, both sides with proper limit,
∫F0dF=μ0i1i22π∫a+ba1xdx
⇒F=μ0i1i22πln(a+ba)
Since, the direction of the force is along +^j direction,
∴→F=μ0i1i22πln(a+ba)^j
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Hence, (D) is the correct answer.
Why this question?
To understand the concept of force between two straight current carrying conductors.