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A matel wire PQ of mass 10g lies at rest...

A matel wire PQ of mass 10g lies at rest on two horizontal metal rails separated by 4.90 cm . A vertically downward magnetic field of magnitude 0.800 T exists in the space. The resistance of the circuit is slowly decreased and it is found that when the resistance goes below`20.0 Omega`, the wire PQ starts sliding on the rails. Find the coefficient of friction.

Text Solution

Verified by Experts

The wire starts sliding when magnetic force on the wire overcomes friction force.
`muN=F implies mumg=ilB`
`muxx.10xx10^-3xx10=6/20xx5xx10^-2xx0.8`
`mu=(6xx5xx10^-2xx0.8)/(20xx0.10xx10^-3xx10)=0.12`
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