Question

A 100 watt electric bulb is used for 5 hours daily and four 60 watt bulbs are used for 5 hours daily. calculate the energy e (in kWh) in the month of January
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Answer 1

ENERGY USED IS 52.7 kWhr

Given:

• One 100 watt bulb used for 5 hr daily.
• Four 60 watt bulbs used for 5 hr daily.

To find:

Total energy consumption?

Calculation:

Let's assume that the four 60 watt bulbs are connected in parallel connection such that the net power will be added.

So, energy consumed in one day by those bulbs will be :

$E1 = (60 + 60 + 60 + 60) \times 5$

$\implies E1 = 240 \times 5$

$\implies E1 = 1200 \: watt \: hr$

$\implies E1 = 1.2 \: kwhr$

Now, the net energy used in 1 day:

$E_{net} = E1 + E2$

$\implies E_{net} = 1.2 + \dfrac{(100 \times 5)}{1000}$

$\implies E_{net} = 1.2 + 0.5$

$\implies E_{net} = 1.7 \: kw hr$

So, energy in January (i.e. 31 days)

$\implies E_{jan} = 1.7 \times 31$

$\implies E_{jan} =52.7 \: kwhr$

So, net energy used in January is 52.7 kWhr.