Question

An unmagnetized steel bar buried in the earth in the north-south direction would, after a few days, exhibit magnetic properties, making it a weak magnet.
Explain by giving reasons how this is possible.
In what way will the effect be different if the steel bar is to be placed above the surface of the earth?

Answer 1

1. The iron filings cling to the iron bar when a bar magnet is brought near it, indicating that it has become a magnet itself.
2. When the bar magnet is removed, the iron filings which were attached to the iron bar fall back into the bowl, indicating that the soft iron bar has lost its magnetism.
3. The process in which a magnetic substance becomes a magnet when it is kept near a magnet without there being physical contact between them is called magnetic induction.
4. Similarly, inside the Earth, the steel bar gets magnetized, whereas, outside it, it loses its magnetism by coming into a weak magnetic field and becoming a steel bar.
   Hence, inside the Earth, the steel bar gets magnetized in a strong magnetic field, whereas outside, it gets demagnetized in a weak magnetic field.