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Matter In Our Surroundings

Question
CBSEENSC9006398

A 100 W electric bulb is lighted for 2 hours everyday and five 40 W tubes are lighted for 4 hours everyday. Calculate,

(i) the energy consumed for 60 days and

(ii) the cost of electricity consumed at the rate of Rs. 3 per kWh. 

Solution

Given, 

100 Watt bulb lighted for 2 hours.
Five 40 Watt tubes are lighted for 4 hours everyday.

(i) Energy consumed by a 100 W bulb each day is,

          E= 100 W x 2 h

            = 200  Wh

            = 2001000 

            =  0.2  kWh


Energy consumed by five 40 W tubes each day, 

              E = 5 x 40 W x 4 h

                 = 800  Wh

                 = 8001000 

                 = 0.8 kWh

Therefore,

Total energy consumed each day = 0.2 + 0.8  =  1.0 kWh 

Total energy consumed in 60 days = 1.0 x 60 = 60 kWh

(ii) Cost fo 1 kWh of electricty = Rs. 3

So, cost of 60 kWh = 3 x 60 = Rs. 180.