Difference Between Faradays Law And Lenzs Law

Difference Between Faraday's Law and Lenz's Law

Q: 1. What is the formula for Faraday's and Lenz's law?

Faraday’s Law- emf = $-N \frac{d\Phi}{dt}$Lenz’s Law follows the same formula, with the negative sign indicating opposition to change.

Explore What is Faraday’s and Lenz’s Law along with their Formulas

Faraday’s Law and Lenz’s Law are two key principles in electromagnetism. Faraday’s Law explains how a changing magnetic field induces an electric current, while Lenz’s Law states that the induced current always opposes the change causing it. Both laws are essential in electrical engineering and physics. Let's explore the differences between Faraday’s law and Lenz’s law along with their applications in simple terms.

Key Differences of Faraday’s Law Vs. Lenz’s Law

Feature	Faraday's Law	Lenz's Law
Definition	Explains how a changing magnetic field induces an electromotive force (emf).	States that the direction of the induced current opposes the change in magnetic flux.
Focus	Deals with the magnitude of induced emf.	Focuses on the direction of induced current.
Formula	emf=−NdΦdt$\text{emf} = -N \dfrac{d\Phi}{dt}$	Same as Faraday’s Law but with a negative sign indicating opposition.
Application	Used in transformers, generators, and induction motors.	Helps determine the direction of current in electromagnetic applications.
Example	Moving a magnet inside a coil induces a current.	The induced current creates a magnetic field opposing the magnet’s motion.

Important Formulas for Faraday's Law and Lenz's Law

Concept	Formula	Explanation
Faraday's Law of Induction	$\text{emf} = -N \dfrac{d\Phi}{dt}$	The induced emf (emf) is proportional to the rate of change of magnetic flux ($\Phi$).
Magnetic Flux ($\Phi$)	$\Phi = B A \cos\theta$	Magnetic flux depends on the magnetic field (B), area (A), and angle ($\theta$).
Lenz’s Law (Opposition to Change)	Same as Faraday’s Law but with a negative sign	The negative sign shows that the induced current opposes the change in magnetic flux.
Induced Current (I)	I = $\dfrac{\text{emf}}{R}$	Induced current is given by Ohm’s law, where R is resistance.
Lorentz Force	F= $q(E + v \times B)$	Force on a charged particle due to electric (E) and magnetic (B) fields.
Fleming’s Right-Hand Rule (Direction of Induced Current)	Thumb → Motion, Index → Magnetic Field, Middle → Current	Used to find the direction of induced current.
Fleming’s Left-Hand Rule (Motor Rule)	Thumb → Force, Index → Magnetic Field, Middle → Current	Used for force direction in electric motors.

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FAQs on Difference Between Faraday's Law and Lenz's Law

1. What is the formula for Faraday's and Lenz's law?

Faraday’s Law- emf = $-N \frac{d\Phi}{dt}$

Lenz’s Law follows the same formula, with the negative sign indicating opposition to change.

2. How is Faraday's law modified by Lenz's law?

Lenz’s Law adds a negative sign to Faraday’s Law, showing that the induced current opposes the change in magnetic flux.

3. What is the SI unit of induced emf?

The SI unit of induced emf (electromotive force) is Volt (V).

4. What is the difference between Faraday's law and Kirchhoff's law?

Faraday’s Law explains electromagnetic induction, while Kirchhoff’s Law deals with current and voltage distribution in electrical circuits.

5. What is the Fleming's right-hand rule?

Fleming’s Right-Hand Rule helps determine the direction of induced current when a conductor moves through a magnetic field.

6. What is the Fleming's left-hand rule?

Fleming’s Left-Hand Rule is used to find the direction of force in a current-carrying conductor inside a magnetic field.

7. What is Lorentz Force in Class 12th?

Lorentz Force is the force experienced by a charged particle moving in a magnetic and electric field, given by F = q(E + v × B).

8. What is electromagnetic induction?

Electromagnetic induction is the process of generating an electric current by changing the magnetic field around a conductor. It is explained by Faraday’s Law.

9. When to use Lenz's law?

Lenz’s Law is used to determine the direction of induced current in electrical circuits, motors, and transformers.

10. What are curie laws?

Curie’s Law states that the magnetisation of a material is directly proportional to the applied magnetic field and inversely proportional to its temperature. The formula is:

M = $\frac{C B}{T}$

where M is magnetisation, C is Curie’s constant, B is the magnetic field, and T is temperature. As temperature increases, magnetism decreases.