Question

Question 28
Describe the activity that shows that a current-carrying conductor experiences a force perpendicular to its length and the external magnetic field. How does Fleming’s left-hand rule help us to find the direction of the force acting on the current carrying conductor?

Answer 1

Activity: To show the effect of magnetic field on current-carrying conductor
Materials Required: For this, we need to take a small aluminum rod, a horse-shoe magnet, battery, plug key, wires and a stand.

Procedure:

a. Take a small aluminum rod AB (of about 5 cm). Using two connecting wires suspend it horizontally from a stand, as shown in Fig.
b. Place a strong horse-shoe magnet in such a way that the rod lies between the two poles with the magnetic field directed upwards. For this put the North Pole of the magnet vertically below and South Pole vertically above the aluminum rod(Figure)
c. Connect the aluminum rod in series with a battery, a key and a rheostat. �
d. Now pass a current through the aluminum rod from end B to end A. �
e. It is observed that the rod is displaced towards the left. You will notice that the rod gets displaced. �

Reverse the direction of current flowing through the rod and observe the direction of its displacement. It is now towards the right

The displacement of the rod in the above activity suggests that a force is exerted on the current-carrying aluminum rod when it is placed in a magnetic field. It also suggests that the direction of force is also reversed when the direction of current through the conductor is reversed.

Fleming’s left-hand rule: According to this rule, stretch the thumb, forefinger and middle finger of your left hand such that they are mutually perpendicular. If the first finger points in the direction of magnetic field and the second finger in the direction of current, then the thumb will point in the direction of motion or the force acting on the conductor.