• A measure of strength of magnetic flux by taking account of number of field lines is
called magnetic flux.
• Magnetic flux density (B) is defined as the ratio of flux passing through a plane perpendicular to
field and the area of the plane.
• Current carrying wire produces magnetic field.
• F = qvB sin θ and F = ILB sinθ
• In electric motor, electrical energy is converted into mechanical energy.
• The production of electric current due to relative motion between a coil and a magnetic field is
called electromagnetic induction.
• Faraday’s law: The induced EMF generated in a closed loop is equal to the rate of change of
magnetic flux passing through it.
• Lenz’s law: the induced current set up in the coil is in such a direction that it opposes the changes
in the flux.
• When a conductor of length ‘l’ moves perpendicular to field B with a speed v then potential
difference (voltage) developed between the ends of conductor is Blv. This EMF is called motional
EMF.
• In generators, mechanical energy is converted into electrical energy.
Reflections on Concepts