Question

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 :

• A. Positive ions deflect towards $+$ Y direction and negative ions towards $-$ Y direction
• B. All ions deflect towards $+$ Y direction
• C. All ions deflect towards $-$ Y direction
• D. Positive ions deflect towards $-$ Y direction and negative ions towards $+$ Y direction

Answer 1

The correct option is C All ions deflect towards $-$ Y direction

As gas is subjected in Electric field. Positive ions will start to move along $+x$ direction and negative ion along $-x$ direction, which implies that current will then be along $+x$ direction. Then using Fleming's left hand rule force will be along $-Y$ direction, they will get deflects towards $-Y$ direction.