Question

(a) On what factors does the force experienced by a straight conductor placed in a magnetic field depend?

(b) State the law which determines the force experienced by a conductor.

Answer 1

Step 1: Factors on which force depends

(a) Factors affecting the force experienced by a straight conductor placed in a magnetic field are listed as follows:

• $F\alpha I$ , the force experienced by the conductor F is directly proportional to the current I.
• $F\alpha B$ , the force experienced by the conductor F is directly proportional to the magnetic field B.
• $F\alpha L$ , the force experienced by the conductor F is directly proportional to the length of the conductor L.

Step 2: Explanation for the law

(b) Fleming's left hand rule determines the force experienced by a conductor.

Fleming's left hand rule statement: If we arrange our thumb, forefinger and middle finger of the left-hand perpendicular to each other, such that the forefinger points towards the direction of the magnetic field and the middle finger points towards the direction of the electric current then the thumb points towards the direction of the force experienced by the conductor.

It can also be stated as, when a current-carrying conductor is placed in an external magnetic field, the conductor experiences a force perpendicular to both the field and to the direction of the current flow.