Question

In a house two 60 Watt bulbs are lighted for 4 hours, and three 100 watt bulbs for 5 hours everyday. calculate the electric energy consumed in 30 days.

plz tell me why 30 days will not be changed to hour

Don't solve fuul ans but tell me then why u hve answered in kwh

Answer 1

2 60W bulb for 4 hrs
per day consumption will be
2*60*4= 480wh

3 100W bulbs for 5 hrs
Per day consumption will be :
3*100*5= 1500wh

Total Per day consuy consumption will be
1500+480 kwh
= 1980wh= 1.98 Kwh

Total consumption for 30 days will be
30*1980
= 59400 What= 59.4 kWh or 59.4 units

Now when u look at the solution , we see that a particular bulb runs for some 4 or 5 hrs / day.
Units of bulb are W and time is Hr
So run time will be Wh!
1Kwh=1 unit= 1000 What

So hence for total consumption we use 1kWh or 1 unit

30 days are not converted to hours because we calculate electricity bill according to energy used in total.
We calculated energy consumption per day and multiplied it by 30 for 30 days. Hence we use days itself because if u convert in hours we ll have it 24 hours usage but we use only a few hours in a day
Hence day is used