Tag: electrical circuits

Questions Related to electrical circuits

If the length of filament of a heater is reduced by  10%, the power of the heater will 

physics electrical circuits domestic electric circuits and safety precautions domestic and commercial circuit electric power

  1. increase by about 9%

  2. increase by about 11%

  3. increase by about 19%

  4. increase by about 10%

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Correct Option: D
Explanation:

$P=\dfrac { { V }^{ 2 } }{ R } \ R=\dfrac { \rho l }{ A } \ \therefore P=\dfrac { { V }^{ 2 }A }{ \rho l } $

$ \therefore P\alpha \dfrac { 1 }{ l } \quad $ [Keep in $\dfrac{v^2A}{\rho }$ constant]
$\therefore$ with reduction of $l$ by $10\%$ power will increase by $10\%$.