WBJEE · Physics · Current Electricity
Heat is produced at a rate given by \(H\) in a resistor when it is connected across a supply of voltage \(V\). If now the resistance of the resistor is doubled and the supply voltage is made \(V / 3\), then the rate of production of heat in the resistor will be
- A \(H / 18\)
- B \(H / 9\)
- C \(6 \mathrm{H}\)
- D \(18 H\)
Answer & Solution
Correct Answer
(A) \(H / 18\)
Step-by-step Solution
Detailed explanation
We know \(H=\frac{V^{2}}{R}\) Here, in second condition \(V\) becomes \(\frac{V}{3}\) and \(R^{\prime}\) becomes \(2 R\). So, \[ \begin{array}{l} H^{\prime}=\frac{\left(\frac{V}{3}\right)^{2}}{2 R}=\frac{V^{2}}{18 R} \\ H^{\prime}=\frac{H}{18} \end{array} \]
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