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  4. A straight horizontal conducting rod of length 50 cm and mass 50 gm is suspended by two vertical wires at its ends. A current of 5.0 A is set up in the rod through the wires. What magnetic field should be set up normal to the conductor in order that the tension in the wires is zero ? (Take g =10 ms -2 )

Q. A straight horizontal conducting rod of length $50\, cm$ and mass $50\, gm$ is suspended by two vertical wires at its ends. A current of $5.0 \, A$ is set up in the rod through the wires. What magnetic field should be set up normal to the conductor in order that the tension in the wires is zero ? (Take $g =10\, ms ^{-2}$ )

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Solution:

For tension to be zero, $m g=B I l$
$B=\frac{m g}{I l}=0.2 T$

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