Question

How much power is dissipated in the circuit when all the three bulbs glow together?

• A. 4.5 W
• B. 15 W
• C. 13.5 W
• D. 0.15 W

Answer 1

The correct option is C 13.5 W

If a certain amount of power is dissipated for a given time, then energy is dissipated. Energy ($power\times time$) is measured in Joules and by including time (t) in the power formulae, the energy dissipated by a component or circuit can be calculated.
Energy dissipated $=Pt$ or $VI\times t$ Ignoring the time factor we get the value of power as $P=VI.$
In this case, the voltage is given as 4.5 V and the current across the resistances is 3 A.
Therefore, poweer dissipated is given as $P=4.5V\times 3A=13.5W$.
Hence, power dissipated in the circuit when all the three bulbs glow together is given as 13.5 W.