How much money can be saved per month by using a compact fluorescent lamp of 15 W in place of an incandescent bulb of 100 W if they are used 8 hours per day for 30 days? (Take the cost of one unit of electrical energy as ₹2)

Open in App

Solution

Step 1: Given data
Power consumption of the lamp, $P_{1} = 15 W$
Power consumption of the bulb, $P_{2} = 100 W$
Time consumed $=$ $8$ hours per day for $30$ days
$= 8 \times 30 = 240 h r$
The cost of one unit of electrical energy is $₹ 2$
Step 2: Finding Units of electricity used
Units of electricity used by the lamp $= P_{1} \times$ time
$= 15 \times 240 = 3600 W h = 3.6 k W h = 3.6 u n i t s$
Units of electricity used by the bulb $= P_{2} \times$ time
$= 100 \times 240 = 24000 W h = 24 k W h = 24 u n i t s$
Step 3: Finding money saved per month
Cost of electricity used by lamp $=$ Units of electricity used by the lamp $\times$ Cost of one unit of electrical energy
$= 3.6 \times 2 = ₹ 7.2$
Cost of electricity used by bulb $=$ Units of electricity used by the lamp $\times$ Cost of one unit of electrical energy
$= 24 \times 2 = ₹ 48$
The difference in money $= 48 - 7.2$
$= ₹ 40.80$
Hence, $₹ 40.80$ money can be saved per month by using a compact fluorescent lamp of 15 W in place of an incandescent bulb of 100 W if they are used 8 hours per day for 30 days.

Suggest Corrections

Similar questions

A bulb of 30 W is switched ON for 15 hours per day. How much electrical energy is consumed in the month of June?

Five LED bulbs of 8 W each, two fans of 40 W each, electric motor 3kW and a geyser of 5 kW are used for 8 hours per day by a family. Calculate the total energy consumed in 30 days and the cost of electricity used in one day at the rate of Rs.5 per unit.

Seeta says that a compact fluorescent lamp uses less energy compared to an incandescent bulb. But Geeta, her friend, does not agree with this. Seeta proves it by calculating the money that can be saved per month by using a compact fluorescent lamp of $15 W$ in place of an incandescent lamp of $100 W$ if they are used $8 h o u r s$ per day for $30 d a y s$ . How did she prove it? (The cost of one unit of electrical energy is $2 r u p e e s$ )

A fluorescent lamp of $20 W$ and an incandescent bulb of $150 W$ are used for $5$ hours per day in the month of February $2008$ . If the cost of one unit of electrical energy is $₹ 1.5$ , which of the two is more economical to use and by how much?