The energy dissipated by a resistor is 10 mJ in 1 s when an electric current of 2 mA flows through it. The resistance is ___________$\Omega$. (Round off to the Nearest Integer)
Answer (integer)
2500
Solution
<p>Given, energy dissipated by a resistor, H = 10 mJ = 10 $\times$ 10<sup>$-$3</sup> J</p>
<p>Time, t = 1 s</p>
<p>Electric current, I = 2 mA = 2 $\times$ 10<sup>$-$3</sup> A</p>
<p>Resistance, R = ?</p>
<p>According to Joule's law of heating,</p>
<p>H = I<sup>2</sup>Rt</p>
<p>$\Rightarrow R = {H \over {{I^2}T}}$ ....... (i)</p>
<p>Substituting the given values in Eq. (i), we get</p>
<p>$R = {{10 \times {{10}^{ - 3}}} \over {{{(2 \times {{10}^{ - 3}})}^2} \times 1}}$</p>
<p>$$ \Rightarrow R = {{{{10}^{ - 2}}} \over {4 \times {{10}^{ - 6}}}} \Rightarrow R = 0.25 \times {10^4}$$</p>
<p>$\Rightarrow R = 2500\,\Omega$</p>
About this question
Subject: Physics · Chapter: Current Electricity · Topic: Ohm's Law and Resistance
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