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A 250 turn rectangular coil of length 2.1 cm and width 1.25 cm carries a current Of 0.85 mu_A and subjected to a magnetic field of strength 0.85 T. Work done for rotating the coil by 180° against the torque is ....... |
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Answer» `4.55 mu J` `W= mB [ cos theta_(1) - cos theta_(2) ]` `= mB [ cos 0^(@) - cos 180^(@) ]` `= mB [1 - (-1) ]` `= mB [2]` `= 2mB = 2 NIAB""[because m= NIA]` `2 xx 250 xx 85 xx 10^(-6) xx 2.1 xx 10^(-2)xx 1.25 xx 10^(-2) xx 0.85` `= 94828.125 xx 10^(-10) ~~ 9.5 xx 10^(-6)` J `= 9.5 mu`J nearer value is in OPTION (D). |
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