Current Electricity - Result Question 71
76. Power dissipated across the $8 \Omega$ resistor in the circuit shown here is 2 watt. The power dissipated in watt units across the $3 \Omega$ resistor is
(a) 1.0
(b) 0.5
(c) 3.0
(d) 2.0
[2006]
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Answer:
Correct Answer: 76. (c)
Solution:
- (c) Power $=V \cdot I=I^{2} R$
$i_2=\sqrt{\frac{\text{ Power }}{R}}=\sqrt{\frac{2}{8}}=\sqrt{\frac{1}{4}}=\frac{1}{2} A$
Potential over $8 \Omega=Ri_2=8 \times \frac{1}{2}=4 V$
This is the potential over parallel branch. So,
$i_1=\frac{4}{4}=1 A$
Power of $3 \Omega=i_1{ }^{2} R=1 \times 1 \times 3=3 W$
