Question

A room has two tube lights, a fan and a TV. Each tube light draws 40 W, fan draws 800 W and TV draws 60 W. On the average tube lights are kept on for 5 hours, fan for 12 hours and TV for 8 hours every day. The rate of electrical energy is Rs. 3 per kwh. Calculate cost of electricity used in this room in a month of june.

Answer 1

Answer:

The total power two tube lights consume = 40+40

= 80W

Power × hours = Wh

80 × 5 = 400Wh

To convert into kWh, multiply and divide by 1000

= 400Wh × 1000/1000

= 400kWh /1000        (As 1000 = k)

= 0.4kWh

This is the kWh the tube lights consumed per day.

For one month, multiply kWh of one day with 30.

Hence,

kWh of one month = 0.4 × 30

= 12kWh

Therefore, tube lights consume total 12kWh in one month.

Similarly, for the TV and fan.

Watt-hours = 60 ×8

= 480Wh

To convert into kWh, multiply and divide by 1000

kWh = 480Wh × 1000/1000

= 480kWh/1000  (As 1000 = k)

          =0.48kWh

This is the kWh the TV consumed per day.

For one month, multiply kWh of one day with 30.

Hence,

= 0.48 × 30

=14.4kWh

Similarly for fan,

Watt-hours = 80 × 12

=960Wh

To convert into kWh, multiply and divide by 1000

kWh = 960Wh × 1000/1000

= 960kWh/1000  (As 1000 = k)

=0.96kWh

This is the kWh the fan consumed per day.

For one month, multiply kWh of one day with 30.

Hence,

= 0.96 ×30

=28.8kWh

Total kWh consumed by all of them in one month = 28.8+ 12 + 14.4

= 55.5kWh

Electric energy is 3.10 per kWh.

The cost of electricity = 3.10 × 55.5

=172.07

Answer 2

Answer:-

• The cost of electricity used in the month is 165.6 rupees.

For each tube light, power,

==> P = 40/1000 W

So, the energy consumed by the fan in a day is

➲ u = P x t

➲ u = (40/1000)kW x (5)h

➲ u = 200/1000

➲ u = 0.2kWh

Energy consumed by the fan in a day is

➲ u = P x t

➲ u = (80)W x (12)h

➲ u = (80 W)x(12 h)

➲u = 960/1000

➲u = 0.96 kWh.

Total energy consumed by TV in a day is

➲ u = P x t

➲ u = (60)W x (8)h

➲ u = 480/1000

➲ u = 0.48kWh

Total energy consumed in a day

➲ 2 x 0.2 kWh + 0.96 kWh + 048 kWh

➲ 1.84 kWh

Energy consumed in a month is

➲ (1.84 kWh) x 30

➲ 55.2 kWh.

The cost of electricity-

➲ Rs (55.2 x 3)

➲ Rs 165.6

Therefore:-

The cost of electricity used in the month is 165.6 rupees.