Question

Power dissipated across the 8 Ω resistor in the circuit shown here is 2 W. The power dissipated in watt units across the 3 Ω resistor is:

• A. 6
• B. 1.5
• C. 0.45
• D. 3

Answer 1

The Correct Option is D

To calculate power, you can use the formula \(P = \frac {V^2}{R}\),
Where V is the voltage and R is the resistance. 
The power dissipated across the 8 Ω resistor is 2 W. 
voltage across the 8 Ω resistor: 
\(2 = \frac {V^2}{8}\)
\(V^2 = 16 \ V\)
\(V =\sqrt { 16} \ V\)
\(V = 4 \ V\)
Now, power dissipated across the 3 Ω resistor:
\(P = \frac {V^2}{R}\)

\(P = \frac {4^2}{3}\) 

P= 16/3 W.