An ionized gas contains both positive and negative ions . If it is subjected simultaneously to an electric field along the ` +x` - direction and a magnetic field along the ` +y` - direction and the negative ions towardws `-y` - direction

Options

A. `+ve` ions deflects towards `+y` and `-ve` ions towards `-y`
B. all ions deflects towards `+y`
C. all ions deflects towards `-y`
D. `+ve` ions deflects towards `-y` and `-ve` ions towards `+y`

Answer

D

Explanation

`rarr vec(E) = E hat(j)`
`o. vec(B) = B hat(k)`
`rarr vec(v) = v_(0) hat(i)`
For `+ve` ions: `vec(F)_(m) = q(v hat(i) xx B hat(k)) = -q v B hat(j)`
For `-ve` ions: `vec(F)_(m) = (-q)(v hat(i) xx Bhat(k)) = qvBhat(j)`