Question

A positively-charged particle (alpha-particle) projected towards west is deflected towards north by a magnetic field. The direction of magnetic field is

• A. Towards south
• B. Towards east
• C. Downward
• D. Upward

Answer 1

The correct option is D

Upward

This question can be solved by using Fleming’s Left Hand Rule. We know that the direction of current is opposite to the direction of electron’s movement and hence, it would be same as the direction of proton’s movement. So, the direction of current is towards west. As per the Fleming’s Left Hand Rule; the middle finger shows the direction of the current, the forefinger shows the direction of magnetic field and the thumb shows the direction of motion. Here, the deflection is towards the north, and hence, the direction of the magnetic field would be in the upward direction.