Magnetism and Electromagnetism
Materials subjected to rapid reversal of magnetism should have

Large area of B-H loop
High co-ercivity and low density
High permeability and low hysteresis loss
High co-ercivity and high retentivity

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Magnetism and Electromagnetism
The magnetomotive force is

The passage of magnetic field through an exciting coil
The sum of all currents embraced by one line of magnetic field
The voltage across the two ends of exciting coil
The flow of an electric current

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Magnetism and Electromagnetism
A certain amount of current flows through a ring shaped coil with fixed number of turns. How does the magnetic induction B varies inside the coil if an iron core is threaded into coil without dimensional change of coil?

Remains same
Decreases
Increases
First increases and then decreases depending on the depth of iron in¬sertion

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