The archean era i think am i right?
An earthquake is the sudden release of energy from the crust of the Earth, that results in a seismic wave. Using a seismograph, the interior of the Earth is mapped, finding the epicenter (origin) and magnitude (strength) of the quake.
Answer:
this is because Steel is more difficult to magnetise and demagnetise but an iron core makes a temporary electromagnet because its lose its magnetism when the switch is open and and steel core is used to make a permanent electromagnet
