Question

Why is iron used as the core of an electromagnet?
Why keepers are used ?
Why we do not see a shadow, when birds and
aeroplanes fly above the earth?
Why the umbra is completely dark while the
penumbra is lighter?​

Answer 1

Answer:

Hello friend...

Soft iron core is used in electromagnets because they get easily magnetised/demagnetised when current is flowing or not flowing along the solenoid.

Frequent drops, impacts or high temperatures weaken it. A piece of iron, called a keeper, fits over the magnet's poles, helping it retain its magnetic strength.