Question: Q. 12. (i) Two long straight parallel conductors ’ $a$ ’ and ’ $b$ ‘, carrying steady currents $I_{a}$ and $I_{b}$ are separated by a distance $d$. Write the magnitude and direction of the magnetic field produced by the conductor ’ $a$ ’ at the points along the conductor ’ $b$ ‘. If the currents are flowing in the same direction, what is the nature and magnitude of the force between the two conductors?
(ii) Show with the help of a diagram how the force between the two conductors would change when the currents in them, flow in the opposite directions.
U[Foreign 2014]
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Solution:
Ans. (i) The magnitude of magnetic field produced by conductor ’ $a$ ’ at a point on the conductor $b$.
$1 / 2$
The direction of magnetic field will be inward / outward perpendicular to the plane of the two conductors, depending on the direction of flow of current in conductor ’ $a$ ‘.
Force per unit length, $\frac{F}{l}=\frac{\mu_{0} I_{a} I_{b}}{2 \pi d}$
Nature : attractive
(ii)
(Any one of the diagram) 1
[CBSE Marking Scheme, 2014]
