Q50 / 256 · NTA Abhyas (NEET) 2020 · Physics · Current Electricity

If in the circuit, power dissipation is $150 W$ , then $R$ is

A
$2 Ω$
Correct answer
B
$6 Ω$
C
$5 Ω$
D
$4 Ω$

Solution

Power

= \frac{V^{2}}{R}

150 = \frac{V^{2}}{R_{net}}

= \frac{15^{2}}{R_{net}}

\frac{1}{R_{net}} = \frac{1}{R} + \frac{1}{2}

∴ R_{net} = \frac{2 R}{R + 2}

∴ 150 = \frac{15^{2} (R + 2)}{2 R}

∴ R = 6 Ω

Hence, the correct answer is option: 'B'.

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