Question:

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 :-

Updated On: Jun 7, 2022
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The Correct Option is A

Solution and Explanation

As voltage drop across
$8 \Omega=\sqrt{2 \times 8}=4 V \left(\because P =\frac{ V ^{2}}{ R }\right)$
Therefore voltage drop across $3 \Omega=3 V$
$[\because 4 V$ is divided in ratio of resistances between $1 \Omega$ and $3 \Omega]$
Hence power dissipated in $3 \Omega=\frac{(3)^{2}}{3}=3$ watt
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Concepts Used:

Electric Power

Power is defined as the rate of doing work. Electric power is the rate at which electrical energy is transferred through an electric circuit, i.e. the rate of transfer of electricity. The symbol for Electric Power is ‘P’. SI unit of electric power is Watt. 

Electric Power Formula

P = VI 

From Ohm's Law, V = IR

Hence, Power can also be expressed as P = I2R