Paheli had heard that rainwater is as good as distilled water. So she collected some rainwater in a clean glass tumbler and tested it using a tester. To her surprise she found that the compass needle showed deflection. What could be the reasons?

AcademicPhysicsNCERTClass 8

Given:

Paheli collected some rainwater in a clean glass tumbler and tested it using a tester. To her surprise, she found that the compass needle showed deflection.

To do:

We have to discuss the possible cause of the deflection of a tester's compass needle.

Solution:

Let us know the conduction of electric current through distilled water and rainwater:

Distilled water does not carry electric current:

Pure or distilled water is a bad or poor conductor of electricity. The electric current can not pass through distilled water if the free ends of wires connected to a battery are immersed in distilled water. So, there is no deflection in the compass needle while using a tester to check the conduction of electricity in distilled water.

Rainwater is a good conductor of electricity:

When rainwater falls on the earth, various types of impurities like salts and acidic gases such as carbon dioxide, sulfur dioxide, etc get dissolved in it. They form ions and these ions make it possible for an electric current to pass through the solution. This solution is known as an electrolyte that contains chlorine and sodium ions that conducts electric current. Thus, rainwater becomes a good conductor of electricity.

Reason for deflection in compass needle:

Rainwater can be as good as distilled water but rainwater is a good conductor of electricity due to mixed impurities in it. Hence, the compass needle shows deflection.

raja
Updated on 10-Oct-2022 13:25:09

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