Question

An electric device of 50 W is made to run for $20h$ per day. If one unit costs $₹2.50$, then the electric bill for the month of November is $₹$

• A. $125$
• B. $150$
• C. $75$
• D. $50$

Answer 1

The correct option is C

$75$

Step 1: Given Data-

Power, $P=50W$

Time, $t=20hoursperday$

$\Rightarrow 20\times 30=600hours$

Step 2: Calculation of Energy

$$\begin{gathered} Power=\frac{energy}{time} \\ energy=power\times time \end{gathered}$$

substitute the given values

$$\begin{gathered} energy=50\times 600 \\ E=30,000Wperhr \end{gathered}$$

Step 3 - Convert the energy into a commercial unit

$$\begin{gathered} 1000wattperhr=1kWh \\ 30,000wattperhr=30kWh \end{gathered}$$

Step 4 - Calculate the amount of the energy consumed

Rate - $₹2.50perunit$

$$\begin{gathered} amount=rate\times energy \\ amount=2.50\times 30 \end{gathered}$$

$amount=₹75$

Therefore, the bill for November month will be$₹75$ for the bulb of $75W$ which runs for $20hr$per day.