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

Answer: (D)

3

Answer 2

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.