Lenz's law and eddy currents
- 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… Answer: 3. A and C only Key idea: A force is needed only if the magnetic pole exerts a force on the sheet. A: A magnetic sheet is attracted... 1
- In the above diagram, a strong bar magnet is moving towards solenoid-2 from solenoid-1. The direction of induced current in solenoid-1 and that in solenoid-2, respectively, are through the directions: Answer: 2. AB and DC Key idea: Lenz's law: the induced current opposes the change in flux, so a solenoid end facing a moving magnet behaves... 1
- In which of the following devices, the eddy current effect is not used ? Answer: 3. electromagnet or 4. electric heater Eddy currents are induced in a conductor by a changing magnetic flux. Induction furnace: eddy... 1