A straight wire of length l can slide on two parallel plastic rails kept in a horizontal plane with a separation d. The coefficient of friction between the wire and the rails is $μ$ . If the wire carries a current i, what minimum magnetic field should exist in the space in order to slide the wire on the rails.

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Solution

The minimum magnetic force = Friction force of the body

$μ m g = i B l$

$B = \frac{μ m g}{i l}$

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The minimum magnetic force = Friction force of the body μmg=iBl B=μmgil

The minimum magnetic force = Friction force of the body

$μ m g = i B l$

$B = \frac{μ m g}{i l}$