A positively-charged particle (alpha-particle) projected towards west is deflected towards north by a magnetic field. The direction of magnetic field is in which direction?
Here the direction of current toward west and towards north .So by Fleming left hand rule the direction of magnetic field is upward. the rule used in Fleming left hand rule which states that if we stretch our thumb forefinger and middle figure of our left hand perpendicular to each other in such a way that forefinger points the direction of magnetic field and middle figure points the direction of current and middle figure points the direction of current then thumb will represent the direction of force.
So Upward is the correct answer.