Question 213: Magnetism and Matter

Question

As shown in the figure, two infinitely long, identical wires are bent by 90
o
and placed in such a way that the segments LP and QM are along the x-axis, while segments PS and QN are parallel to the y-axis. If OP = OQ = 4cm, and the magnitude of the magnetic field at O is 10
–4
T, and the two wires carry equal
currents (see figure), the magnitude of the current in each wire and the direction of the magnetic field at O will be ($\mu $
0
= 4$\pi $ $ 	imes $ 10
–7
NA
–2
) :
![](https://imagex.cdn.examgoal.net/Hnj9foF24K4nr1CTW/9YBrNfedKO6DcNq2RzLF3MrRjgd8y/3SadEg8fTxgdRf1cJpLjyh/image.png)

Accepted Answer

Magnetic field at 'O' will be done to 'PS' and 'QN' Only
i.e. B
0
= B
PS
+ B
QN
$ 	o $ Both inwards
Let current in each wire = i
$ 	herefore $  B
0
= ${{{\mu _0}i} \over {4\pi d}} + {{{\mu _0}i} \over {4\pi d}}$
or      10
$-$4
= ${{{\mu _0}i} \over {2\pi d}}$ = ${{2 	imes {{10}^{ - 7}} 	imes i} \over {4 	imes {{10}^{ - 2}}}}$
$ 	herefore $       i = 20 A

Answer

40 A, perpendicular into the page

Answer

40 A, perpendicular out of the page

Answer

20 A, perpendicular into the page

Answer

40 A, perpendicular out of the page

Magnetism and Matter

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