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TS EAMCET · Physics · Current Electricity

A \(100 \mathrm{~W}\) tungsten light bulb has a resistance of \(250 \Omega\) when it as turned ON and \(25 \Omega\) when turned OFF. The ambient room temperature is \(25^{\circ} \mathrm{C}\). Find the temperature of the filament when the bulb is turned ON. \(\left(\right.\) Let \(\left.\alpha_{\text {tungsten }}=4.5 \times 10^{-3} /{ }^{\circ} \mathrm{C}\right)\)

  1. A \(2600^{\circ} \mathrm{C}\)
  2. B \(2025^{\circ} \mathrm{C}\)
  3. C \(2500^{\circ} \mathrm{C}\)
  4. D \(2625^{\circ} \mathrm{C}\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(2025^{\circ} \mathrm{C}\)

Step-by-step Solution

Detailed explanation

If \(t_2\) and \(t_1\) be the temperature of filament, when light bulb is turned ON and turned OFF, respectively then, \(\begin{aligned} R_{t_2} & =250 \Omega \\ R_{t_1} & =25 \Omega \\ \alpha_{\text {tungsten }} & =4.5 \times 10^{-3} / \mathrm{C}\end{aligned}\) We know that,…