#### 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 +z direction, then Option 1) Positive ions deflect towards +y direction and negative ions towards -y direction   Option 2)  All ions deflect towards +y direction   Option 3) All ions deflect towards -y direction   Option 4) Positive ions deflect towards -y direction and negative ions towards +y direction

As we learnt in

Force on a current carrying conductor -

- wherein

idl=current element

Due to electric field positive ion will move along +x direction and -ve ion along -x direction.

Since magnetic field is along +z direction, it will apply force in -y direction for both positive and negative ion.

Option 1)

Positive ions deflect towards +y direction and negative ions towards -y direction

incorrect

Option 2)

All ions deflect towards +y direction

incorrect

Option 3)

All ions deflect towards -y direction

correct

Option 4)

Positive ions deflect towards -y direction and negative ions towards +y direction

incorrect