Q4 of 26 Page 134

Sometimes, a crackling sound is heard while taking off sweater during winter. Explain.

The crackling sound is heard due to electric discharge between sweater and body. The sweater is made up of wool and the shirt we wear is made up of cotton blended with some synthetic fibers. When we take out the sweater the friction is developed and the transfer of electrons take place from shirt to sweater, this results in building of electric potential.

When enough potential has been accumulated while taking of the sweater it discharges and transfer of electrons take place. This transfer of electrons forms spark and let out sound energy and heat energy. Thus we hear the crackling sound and in dark room we may see the spark lights as well.


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