Question

Lenz's law gives

• A. direction of the magnetic field line at any point
• B. magnetic force acting on a current carrying wire in magnetic field
• C. direction of induced current
• D. pole strength of the bar magnet

Answer 1

The Correct Option is C

Step 1: Recall Lenz's Law.

Lenz's Law is a fundamental principle in electromagnetism that describes the direction of an induced current. It states that:

The induced current in a conductor will flow in such a direction as to oppose the change that produced it.

This law helps determine the direction of the induced current when a magnetic field changes or a conductor moves through a magnetic field.

Step 2: Analyze the options.

• (1) Direction of the magnetic field line at any point: This is determined by the right-hand rule for magnetic fields, not Lenz's Law.
• (2) Magnetic force acting on a current-carrying wire in a magnetic field: The magnetic force on a current-carrying wire is given by the formula \( F = I \cdot L \cdot B \sin\theta \), where \( I \) is the current, \( L \) is the length of the wire, \( B \) is the magnetic field strength, and \( \theta \) is the angle between the wire and the magnetic field. This is described by the Lorentz force law, not Lenz's Law.
• (3) Direction of induced current: Lenz's Law specifically determines the direction of the induced current in response to a changing magnetic field or motion through a magnetic field. This is the correct application of Lenz's Law.
• (4) Pole strength of the bar magnet: The pole strength of a bar magnet is related to its magnetic moment and is not directly determined by Lenz's Law.

Final Answer: Lenz's Law gives the \( \mathbf{\text{direction of induced current}} \), which corresponds to option \( \mathbf{(3)} \).

Answer 2

Lenz’s Law states that the direction of the induced current is such that it opposes the change in magnetic flux that caused it. It is a qualitative law and does not give the magnitude of the EMF or the strength of the magnetic field. Instead, it helps determine the **direction** of the induced current. This is consistent with the negative sign in Faraday’s Law of Electromagnetic Induction: \[ \mathcal{E} = -\frac{d\Phi_B}{dt} \] The negative sign indicates the opposing nature, as stated by Lenz’s Law.