There is a non-conducting disc of mass 4kg and radius 1m placed on a rough non conducting surface. A conducting ring of same mass is tightly fixed around the disc. There exists a magnetic field vecB=4hati+4t^(2)hatj. The resistance of the ring is 8Omega. Find the time after which the system will start toppling.

There is a non-conducting disc of mass 4kg and radius 1m placed on a r

1.	There is a non-conducting disc of mass 4kg and radius 1m placed on a rough non conducting surface. A conducting ring of same mass is tightly fixed around the disc. There exists a magnetic field vecB=4hati+4t^(2)hatj. The resistance of the ring is 8Omega. Find the time after which the system will start toppling.
Answer» Solution :Now `i=(EPSILON)/R=(pir^(2))/R (dB)/(DT)` `\|bar(tau)\|=\|barMxxbarB\|=2mgr` `(pir^(2))/R (dB)/(dt).pir^(2).4=2mg.r` `4(PI^(2)r^(4))/R.8t=2mg.r` `t=2`SEC

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