Q31 of 92 Page 2

A square loop PQRS carrying a current of 6.0 A is placed near long wire carrying 10 A as shown in figure (35-E10). A Show that the magnetic force acting on the part PQ is equal and opposite to that on the part RS. B Find the magnetic force on the square loop.


Here, current in the wire is


Current in the loop,


Force on an element dx in the arm PQ a distance x away is




similarly, force on RS is,



Hence,.


B distance of PS from wire,


distance of PS from RQ,


Force on element PS is



towards right


Now distance of RQ from wire,


distance of RQ from PS,


similarly, force on RQ is



towards left


Net force,


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29

Figure shows a part of an electric circuit. The wires AB, CD and EF are long and have identical resistances. The separation between the neighboring wires is 1.0 cm. The wires AE and BF have negligible resistance and the ammeter reads 30 A. Calculate the magnetic force per unit length of AB and CD.


 30

A long, straight wire is fixed horizontally and carries a current of 50.0 A. A second wire having linear mass density 1.0 × 10–4 kg m–1 is placed parallel to and directly above this wire at a separation of 5.0 mm. What current should this second wire carry such that the magnetic repulsion can balance its weight?

. A square loop PQRS carrying a current of 6.0 A is placed near a long wire carrying 10 A as shown in the figure.


(a) Show that the magnetic force acting on the part PQ is equal and opposite to that on the part Rs.


(b) Find the magnetic force on the square loop.



 32

A circular loop of one turn carries a current of 5.00 A. If the magnetic field B at the centre is 0.200 mT, find the radius of the loop.

 33

A current carrying circular coil of 100 turns and radius 5.0 cm produces a magnetic field of 6.0 × 10–3 T at its centre. Find the value of the current.