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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:
A
A, C and D only
B
C only
C
B and D only
D
A and C only
Detailed Solution
A. A magnetic sheet experiences a magnetic force (attraction) near the pole, so a force is needed to hold it there – correct.
B. A non-magnetic sheet does not interact significantly with the magnetic field, so no force is needed to hold it – incorrect.
C. When a conducting sheet is moved away from the pole, eddy currents are induced which oppose the motion (Lenz's law), so a force is needed to keep it moving with uniform velocity – correct.
D. A non-conducting, non-polar sheet does not interact significantly with the magnetic field, so no force is needed – incorrect.
So A and C only are correct.