Question

Five $100\text{W}$ bulbs are used for $10\text{hr}$ every day for $30\text{days}$. If the rate of electricity is $\text{Rs.}4.00/\text{unit}$, find the cost of electricity.

• A. $\text{Rs.}300$
• B. $\text{Rs.}600$
• C. $\text{Rs.}450$
• D. $\text{Rs.}900$

Answer 1

The correct option is B $\text{Rs.}600$

For each bulb, power, $P=100\text{W}=0.1\text{kW}$

So, total energy used by five bulbs,
$E=5\times 0.1\times 10\times 30=150\text{kWh}=150\text{unit}$

So, cost of electricity $=150\times 4=\text{Rs.}600$