(a) The force required to remove the sheet increases with increase in speed due to change in magnetic flux.
(b) The area in the magnetic field changes as the sheet is being put in between the poles. Thus, a force would be required to put the sheets.
When the sheet is pulled out, from the electromagnet there is change in magnetic flux given as follows;
Ф = BA
where;
emf = dФ/dt
F = qVB
Thus, the force required to remove the sheet increases with increase in speed due to change in magnetic flux.
Also, the area in the magnetic field changes as the sheet is being put in between the poles. Thus, a force would be required to put the sheets.
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