A metallic block carrying current `I` is subjected to a uniform magnetic induction `vec(B) as shown in Figure . The moving charges experience a force ` vec(F) given by ….. Which results in the lowering of the potential of the face ……. Assume the speed of the carries to be `v` .

Options

A. `eVBhat(k), ABCD`
B. `eVBhat(k)EFGH`
C. `-eVBhat(k),ABCD`
D. `-eVBhat(k),EFGH`

Answer

1

Explanation

As the block is of metal, the charge carriers are electrons, so for current along positive `x-` axis, the electrons are moving along negative `x-` axis,
`i.e.vec(v)=- v hat(i)`
and as the magnetic field is along the `y-` axis, `i.e.vec(B)=Bj`
So `vec(F)=q(vec(v)xx(B))` for this case yield
`vec(F)=(-e)[-vhat(i)xxBhat(j)]`
`i.e., vec(F)=evBhat(k)[Ashat(i)xxhat(j)=hat(k)]`

As force on electrons is towards the face `ABCD`, the electrons will accumulate on its hence it will acquire lower potential.