Page 8 - 10-phy-15 Electromagnetism

15. Electromagnetism eLearn.Punjab

Michael Faraday discovered that the force on the wire is at right angles to both the direction of the
magnetic field and the direction of the current. The force is increased if
• The current in the wire is increased
• Strength of magnetic field is increased
• The length of the wire inside the magnetic field is increased

Determining the direction of force

Faraday s description of the force on a current-carrying wire does not completely specify the
direction of force because the force can be towards left or towards right. The direction of the force
on a
current-carrying wire in a magnetic field can be found by using Fleming’s left hand rule stated as:

Stretch the thumb, forefinger and the
middle finger of the left hand mutually

perpendicular to each other. If the
forefinger points in the direction of the
magnetic field, the middle finger in the
direction of the current, then the thumb
would indicate the direction of the force

acting on the conductor.

Animation 15.5 : Force on a Current-Carrying
Conductor Placed in a Magnetic Field
Source & Credit : nsw

As shown in Fig.15.7, the force acting on the conductor is at right Fig. 15.7: Direction of force on a
angle to both the directions of current and magnetic field according current-carrying conductor
to Fleming’s left hand rule. placed in a magnetic field

8 V: 1.1