(N/A) Activity: Take a small aluminum rod $AB$ suspended horizontally from a stand using two connecting wires. Place a strong horseshoe magnet in such a way that the rod lies between the two poles with the magnetic field directed upwards. Connect the rod $AB$ in series with a battery,a key,and a rheostat. When current is passed through the rod from $B$ to $A$,the rod is observed to get displaced. This displacement shows that a force is acting on the current-carrying conductor when it is placed in a magnetic field. The direction of this force is perpendicular to both the length of the conductor and the magnetic field.
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 forefinger points in the direction of the magnetic field and the middle finger points in the direction of the current,then the thumb will point in the direction of the motion or the force acting on the conductor.