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Two long parallel wires X and Y, separated by a distance of 6 cm , carry currents of 5A and 4A, respectively, in opposite directions as shown in the figure. Magnitude of the resultant magnetic field at point P at a distance of 4 cm from wire Y is $$x \times 10^{-5}T$$. The value of is__________ . Take permeability of free space as
$$\mu_{\circ}=4\pi \times 10^{-7}$$SI units.
Correct Answer: 1
$$I_X = 5 \text{ A}$$
$$I_Y = 4 \text{ A}$$
Distance between wires X and Y is $$6 \text{ cm}$$
Point P is at a distance of $$4 \text{ cm}$$ to the right of wire Y.
The total distance of point P from wire X is:
$$ r_X = 6 \text{ cm} + 4 \text{ cm} = 10 \text{ cm} = 0.1 \text{ m} $$
The distance of point P from wire Y is:
$$ r_Y = 4 \text{ cm} = 0.04 \text{ m} $$
The magnetic field due to a long straight wire is given by the formula:
$$ B = \frac{\mu_0 I}{2\pi r} $$
Calculate the magnetic field at point P due to wire X ($$B_X$$):
$$ B_X = \frac{4\pi \times 10^{-7} \times 5}{2\pi \times 0.1} $$
$$ B_X = \frac{2 \times 10^{-7} \times 5}{0.1} $$
$$ B_X = 10 \times 10^{-6} \text{ T} = 1 \times 10^{-5} \text{ T} $$
By the right-hand grip rule, with current flowing upwards, the direction of $$B_X$$ at point P is into the plane of the paper.
Calculate the magnetic field at point P due to wire Y ($$B_Y$$):
$$ B_Y = \frac{4\pi \times 10^{-7} \times 4}{2\pi \times 0.04} $$
$$ B_Y = \frac{2 \times 10^{-7} \times 4}{0.04} $$
$$ B_Y = 2 \times 10^{-5} \text{ T} $$
By the right-hand grip rule, with current flowing downwards, the direction of $$B_Y$$ at point P is out of the plane of the paper.
Since the magnetic fields are in opposite directions, the resultant magnetic field ($$B_{net}$$) is the difference between their magnitudes:
$$ B_{net} = B_Y - B_X $$
$$ B_{net} = 2 \times 10^{-5} \text{ T} - 1 \times 10^{-5} \text{ T} $$
$$ B_{net} = 1 \times 10^{-5} \text{ T} $$
Comparing this with the given expression $$x \times 10^{-5} \text{ T}$$, we get the value of $$x$$:
$$ x = 1 $$
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