Ques 1) Figure shos a long current carrying wire and two rectangular loops moving with velocity v . Find the direction of current.
Ques 2) A rod of length L is placed prependicular to a long wire carrying current i. The rod is moved parallel to the wire with a velocity v. Find the e.m.g induced in the rod, if it's nearest end is at a distance 'a' from the wire.
Ques 3) A thin non conducting ring of mass m carrying a charge q can rotate freely abt its axis. At t=0, the ring was at rest and no magnetic field was present. Then suddently a magnetic field B was set perpendicular to the plane. Find the angular velcoity acquired by the ring.
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2 Answers
106Q1. (i) zero ?
(ii) clockwise
Q2. there is no separate magnetic field B naa? the B u have shown is due to wire only? If yes,
then is ans\frac{\mu_{o}Iv}{2\pi}ln(1+\frac{a}{l})
Q3. induced electric field = E (say)
∫E.dl = -dφ/dt
=> E.2Ï€R = -Ï€R2dB/dt
=> E = R2dB/dt (ignoring - sign)
=> Edt = RdB/2
=> ∫Edt = RB/2
Let it act for time dt
so impulsive torque due to E = (∫Edt).Q.R = mR2ω
=> RB/2 . Q . R = mRRw
=> w = BQ/2m
