Question

(a) What is a magnetic field? How can the direction of magnetic field lines at a place be determined?
(b) State the rule for the direction of the magnetic field produced around a current-carrying conductor. Draw a sketch of the pattern of field lines due to a current flowing through a straight conductor.

Answer 1

(a) The magnetic field is defined as the space surrounding a magnet in which magnetic force is exerted. The direction of magnetic field lines at a place can be determined by finding the deflection in the needle of a magnetic compass.

(b) The rule for determining the direction of the magnetic field of a current carrying wire is the right-hand thumb rule.

Right-hand thumb rule: The right-hand thumb rule indicates the direction of the magnetic field for a know direction of the current. If the thumb of the right-hand points along the direction of current then the curled fingers of that hand gives the direction of the magnetic field due to the current.