Wednesday, 15 May 2013

Why does the cord of an electric heater not glow while the heating element does



Question 1:
Why does the cord of an electric heater not glow while the heating element does?
Solution:
The heating element of the heater is made up of alloy which has very high resistance so when current flows through the heating element, it becomes too hot and glows red. But the resistance of cord which is usually of copper or aluminium is very law so it does not glow.

12 comments:

  1. OK now I understand. Thanx for the help

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  2. Good simple and easy to understand ... Also helped in understanding how to solve these type of questions...

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  3. But according to jules law of heating the one which passes more current will heat up more right? As H proportional to current squared..... So cord should burn with more heat right?....

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    Replies
    1. H=I^2rt
      Since H is directly proportional to resistance,As the resistance increases H also increases..As a result the heating element becomes too hot and it glows!

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    2. H is directly proportional to current square but only if resistance(r)remains same but here r is changing

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  4. Very good answer...
    Easy to understand..
    Thanks for the help..
    ☺️๐Ÿ™๐Ÿ‘Œ

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  5. Can we write this as a bad conductor of heat and electricity

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