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Question
A conducting rod is moved with a constant velocity v in a magnetic field. A potential difference appears across the two ends _____________ .
Options
if `vec v " || "vec l`
if `vec v " || "vec B`
if `vec l " || "vec B`
None of these
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Solution
None of these
The potential difference across the two ends is given by
`e=Bvl`
It is non-zero only
(i) if the rod is moving in the direction perpendicular to the magnetic field `(vec v bot vec B)`
(ii) if the velocity of the rod is in the direction perpendicular to the length of the rod `(vec v bot vec l)`
(iii) if the magnetic field is perpendicular to the length of the rod `vec l bot vec B`
Thus, none of the above conditions is satisfied in the alternatives given.
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