3oh!!! yes ur rite ashish ......Bis goin into the plane of the disc ... ur rite ...
A thin disc or radius R has charge Q distributed uniformly on its surface. The disc is rotated about one of its diametric axis with angular velocity w in a uniform magnetic field of magnitude B directed inward into the plane of the disc at the instant of consideration. Choose the correct alternatives
(a) The magnetic moment of the disc is QR2w/4
(b) The magnetic moment of the disc is QR2w/8
(c) Instantaneous torque acting on the disc is QR2wB/8
(d) Instantaneous torque acting on the disc is zero
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6 Answers
24M/L=q/2m
=>M=qL2m
=>M=qmR2ω4.2m=qR2ω2.4
Torque=TB=MxB=lMl lBl sinθ
SInce θ=0
=>T=0
106eure r u getting M X B as positive ... ? i was getting M and B parallel to each other. . .mayb ill hav to recheck
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