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| Numerical 03 |
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| 03. Two concentric circular coils X and Y of radii 16cm and 10cm respectively lie in the same vertical plane containing the north-south direction. Coil X has 20 turns and carries a current of 16 A; coil Y has 25 turns and carries a current of 18A. The direction of current in X is anticlockwise and in Y is clockwise for an observer looking at the coil facing west. Give the magnitude and direction of the net magnetic field due to the coils at their centre. |
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| Suggested solution: |
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| Let By be the magnetic field at the centre of the coil Y due to the current Iy flowing in it. If Ny be the number of turns and ry the radius of the coil, then |
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| For an observer looking at the coil Y facing west, the current is flowing in the clockwise direction. So, the direction of field By is towards west. |
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| If Bx is the magnetic field at the centre of coil X, then |
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| For an observer looking at the coil X facing west, the current is flowing in the anticlockwise direction. So, the direction of field Bx is towards east. |
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So, the resultant magnetic field
will be in the direction of the bigger of the two vectors. The
magnitude of
i.e., B will be equal to the difference of the magnitude of  |
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Moving Charges and Magnetism
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