JEE Main & Advanced Physics Current Electricity, Charging & Discharging Of Capacitors Question Bank Heating Effect of Current

  • question_answer A heater coil is cut into two parts of equal length and one of them is used in the heater. The ratio of the heat produced by this half coil to that by the original coil is [NCERT 1972; AIEEE 2005; CBSE PMT 2005]

    A)            2 : 1                                          

    B)            1 : 2

    C)            1 : 4                                          

    D)            4 : 1

    Correct Answer: A

    Solution :

               \[P=\frac{{{V}^{2}}}{R}\Rightarrow P\propto \frac{1}{R}\]and\[R\propto l\]             \[\therefore P\propto \frac{1}{l}\Rightarrow \frac{{{P}_{1}}}{{{P}_{2}}}=\frac{{{l}_{1}}}{{{l}_{2}}}=\frac{2}{1}\]

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