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Plz explain while solving the theory also plz 
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Asked by vishakhachandan026 | 31 Mar, 2019, 11:50: AM
answered-by-expert Expert Answer
Power dissipation in a coil of resistance R = i2 R  = V2/ R .......................(1)
 
where V is the constant potentia difference applied across coil and i is the current.
 
resistance of the coil is proportional to length. Hence if 10% length is reduced for the coil of initial resistance R , then the changed resistance is 0.9R
 
Hence changed power dissipation  = V2 /(0.9R) .........................(2)
 
hence the ratio of changed power dissipation to initial power dissipation is obtaied by dividing eqn.(1) by eqn.(2) .
 
Ratio of changed power dissipation to initial power dissipation = begin mathsize 12px style fraction numerator begin display style bevelled fraction numerator V squared over denominator 0.9 R end fraction end style over denominator begin display style bevelled V squared over R end style end fraction space equals space space fraction numerator 1 over denominator 0.9 end fraction space almost equal to space 1.11 end style .......................(3)
From (3), we have, the changed power dissipation is 11% more than initial value
Answered by Thiyagarajan K | 31 Mar, 2019, 14:11: PM

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