A sheet is placed on a horizontal surface in front of a strong magnetic pole. A force is needed to:
(A) hold t

Question

A sheet is placed on a horizontal surface in front of a strong magnetic pole. A force is needed to:
(A) hold the sheet there if it is magnetic.
(B) hold the sheet there if it is non-magnetic.
(C) move the sheet away from the pole with uniform velocity if it is conducting.
(D) move the sheet away from the pole with uniform velocity if it is both, non-conducting and non-polar.

Choose the correct statement(s) from the options given below:

Accepted Answer

1. **Analysis of Statement A:** A magnetic sheet (ferromagnetic or paramagnetic) will be attracted towards the strong magnetic pole due to magnetization. To keep it stationary (hold it there), an external force equal and opposite to the magnetic attraction is required. Thus, **Statement A is correct**.
2. **Analysis of Statement C:** When a conducting sheet is moved near a magnetic pole (where the field is non-uniform), the magnetic flux through the sheet changes. This induces **Eddy Currents** in the sheet. According to **Lenz's Law**, these currents create a magnetic force that opposes the motion of the sheet. To move the sheet with a uniform velocity against this retarding force, an external force is required. Thus, **Statement C is correct**.
3. **Analysis of Statements B and D:** A non-magnetic and non-conducting sheet experiences neither magnetic attraction nor eddy current damping. Therefore, no specific magnetic-related force is needed to hold it or move it (ignoring standard friction/gravity). Thus, Statements B and D are incorrect.
4. **Conclusion:** Both statements A and C are correct.

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