A child staying in a coaster region test the drinking water and also the sea water with its tester he finds that the compass needle deflects more in the case of sea water can you explain the reason?

The reason the compass needle deflects more in the case of sea water is due to the presence of dissolved salts in the water. Sea water contains a high concentration of salts, such as sodium chloride (common table salt), magnesium chloride, and calcium chloride. These salts are electrically charged particles called ions.

When a compass needle is placed near a magnetic field, it aligns itself with the Earth's magnetic field. However, when the compass is placed in sea water, the presence of ions in the water affects the magnetic field around the compass needle.

The ions in the sea water act as conductors of electricity. As the compass needle aligns itself with the Earth's magnetic field, the ions in the sea water create an electric current that opposes the Earth's magnetic field. This opposing current creates a magnetic field of its own, which interacts with the compass needle and causes it to deflect more than it would in pure drinking water.

In simpler terms, the presence of ions in sea water creates an additional magnetic field that interferes with the Earth's magnetic field, leading to a greater deflection of the compass needle.