Question

Which of these will consume most units of energy in a day?

• A. A $60W$ bulb used for $6hrs$.
• B. A $30W$ bulb used for $12hrs$.
• C. A $20W$ bulb used for $24hrs$.
• D. A $100W$ bulb used for $2hrs$.

Answer 1

Answer: (C)

A $20W$ bulb used for $24hrs$.

Energy consumed per day is: $E=P\times t$

where $P$ is power and $t$ is time for which it is used.

A) : $E_A=0.06\times 6=0.36kWh$

(B) : $E_B=0.03\times 12=0.36kWh$

(C) : $E_C=0.02\times 24=0.48kWh$

(D) : $E_D=0.10\times 2=0.20kWh$

Thus, bulb of option C will consume most units of energy in a day.