Describe how an electromagnet can be switched on and off .
Answers
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The short answer is yes, they can be turned on and off. However, there are some which are not intended to be turned off by design. There is no electromagnet before it becomes assembled and energised, so by simple logic we know they can be turned ON.
Turning one OFF requires to stop current flow through an inductor, which by nature will generate a reverse voltage. The kickback voltage is generally absorbed by a diode load placed in parallel with the magnet coil.
Superconducting solenoid magnets used in NMR, MRI and other instrumentation are mostly designed to stay energised virtually forever, and have no OFF switch, per say. That is not to say they cannot be turned off, but just that it is not a design function.
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Answer:
if we remove or cut the electricity source,it can be switched off.if we join the electricity source that we have cut previously,it can be switched on.thank-you