9.4

• Faraday’s law can give the size of the induced voltage in a loop of wire, but it does not describe its direction.
• Lenz’s law also validated the Law of Conservation of Energy and the Third Law of Motion from an electromagnetic vantage.
• Lenz's law- “The magnetic induction effect always opposes its cause”.
• Lenz’s law was formulated by the Russian geophysicist Heinrich Friedrich Emil Lenz.
• Direction of the Induced Current

  The “cause” mentioned in the statements of Lenz’s law, may either be:

  1.a changing magnetic flux caused by the motion of conductor(s) 2.a changing magnetic flux caused by a varying/non-uniform magnetic field in a stationary circuit 3.a combination of both
• 1.In a changing magnetic flux in a motionless/stationary circuit, the induced current will generate its own magnetic field around it. This induced current opposes the direction of the change in magnetic flux through the loop.
• For a changing magnetic flux caused by moving conductors, the induced current generated from the moving conductor will have a direction opposite of the conductors magnetic-field force
• Direction of Induced Current - The direction of this field is always in the opposite direction of the change in flux through the conducting loop
• When the induced magnetic field that opposes the flux change is upward, the induced current is in a counterclockwise direction.
• When the induced magnetic field that opposes the flux change is downward, the induced current must be in a clockwise direction.
• In Lenz’s law, it is the direction of the change in flux and not the flux itself that is taken into consideration
• The change in magnetic flux depends on:

  (1)the direction of the magnetic flux (2)the motion of the magnet
• Lenz’s Law and the Response to Flux Change: Lenz’s law is a qualitative law and aims to predict and describe the direction of the induced current
• Lenz’s Law and the Response to Flux Change: The current’s magnitude ultimately depends on the resistance present in the circuit (Ohm’s Law).
• Lenz’s Law and the Response to Flux Change: ●The amount of induced current that opposes any flux change will be inversely proportional to the resistance present in the system.
• The greater the resistance, the less induced current will flow in the circuit. The lesser the induced current, the greater the change in flux. The same is true for the opposite
• ●The negative sign in the Faraday’s law equation               shows that the direction of the induced emf and current and the change in flux are always in opposite directions. 
• Lenz’s law states that the magnetic induction effect always opposes its cause
• ●For a changing magnetic flux caused by moving conductors, the induced current generated from the moving conductor will have a direction opposite of the conductor’s magnetic-field force.
• ●In the case of a changing magnetic flux in a motionless/stationary circuit, the induced current will generate its own magnetic field around it. This induced current opposes the direction of the change in magnetic flux through the loop.