Current Electricity - Result Question 69

74. A current of $3 amp$ flows through the $2 \Omega$ resistor shown in the circuit. The power dissipated in the $5-\Omega$ resistor is:

(a) 4 watt

(b) 2 watt

(c) 1 watt

(d) 5 watt

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Answer:

Correct Answer: 74. (d)

Solution:

  1. (d) Clearly, $2 \Omega, 4 \Omega$ and ( $1+5) \Omega$ resistors are in parallel. Hence, potential difference is same across each of them.

$\therefore I_1 \times 2=I_2 \times 4=I_3 \times 6$

Given $I_1=3 A \quad \therefore I_1 \times 2=I_3 \times 6$

Given $I_1=3 A$.

$\therefore I_1 \times 2=I_3 \times 6$ provides

$I_3=\frac{I_1 \times 2}{6}=\frac{3 \times 2}{6}=1 A$.

Now, the potential across the $5 \Omega$ resistor is

$V=I_3 \times 5=1 \times 5=5 V$.

$\therefore$ the power dissipated in the $5 \Omega$ resistor

$P=\frac{V^{2}}{R}=\frac{5^{2}}{5}=5$ watt.