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?

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

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Magnetism and Electromagnetism
A permanent magnet

Attracts only ferromagnetic substances
Attracts ferromagnetic substances and repels all others
Attracts some substances and repels others
Attracts all paramagnetic substances and repels others

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