How to calculate the cost of electrical energy consumption(Light bill)⚡….

Guys, have you ever wondered about the light bill that we get every month? And how the electricity bill is being calculated? How does the light bill meter work?🤔 all these stuff we are gonna cover in this article.

At the end of this article, you will be able to find the light bill of your own household 😃 appliances.

So guys now I know that somewhere you have definitely seen this picture below i.e a bulb written 10W or 60W over it. So what does it mean? And which are more efficient 10W or 60W. So, let’s detail this first then will move on to our calculating domestic electricity bill😃.

let’s have some overlook at the units and their calculations.

Different units,

•  work = joule
• Time= second
• Power= joules per second
• Power= volt-ampere
• Power=Watts

Now As we know,

POWER= WORK DONE / TIME

i.e.         P=W / t ———(1)

But        W=V×q ———(from electrostatic)

              W=V×i×t  —-(as i=q/t)  ———(2)

Therefore, 

P= V× i        —-(A)—–(from 1 & 2 ).

Thus, the power of an electrical appliance i.e watts can be found by just multiplying the potential difference in volts and the current in amperes. 

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Different ways of defining the power rating of electrical devices.🙇‍♂️

👉A power rating of 1W bulb means it will consume electrical energy at the rate of 1 joule per second

👉we can say that 1watt is the power consumed by an electrical device when operated at a potential difference (voltage) of 1 volt carries a current of 1 ampere.

👉If an electrical device is operated at a potential difference of 1volt and the device carries a current of 1 ampere, the power becomes 1watt.

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so,

 As power (p) = Workdone / time

           i.e   P = electrical energy(E) /  time(t)

Therefore,   E  = P × t  ——-—-(B)

Also, from (A) we have

P=V× i       ——–(3)

But, V= i×R –——-(4)

also i= V/ R——-(5)

Therefore, 

P= i² × R —(by putting the value of 4 in eq.(3)

                              Or

P= V² / R —(by putting value of 5 in eq (3)

So from the above equation, it is cleared the power of an electrical device is inverse proportional to its resistance (R). 

Like for example, we have two bulbs, one with 10W and the second one with 60W both are connected to AC source (220V), then the resistance of 60W bulb is lesser than that of 10W bulb. Hence, the 60W bulb will glow more brightly as compared to 10W bulb⤵

So in terms of cost-effective the 60W bulb is not beneficial because it has low resistance means draws high current i.e more light bill month.👀

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Guys

Guys the answer is just a little away from you 😃 , First of all, will have to calculate the current drawn by all the 3-appliance and the maximum current drawn by a device will consume more electricity bill😃⤵

Calculating current consumption of devices:

#1 : Heating iron

As we know, 

    P = V× I

750 = 220× I

Therefore,  I= 3.4 ampere (A)

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#2 : Television set

Similarly, 

     P= V× I

  50 =220×I

Therefore, I= 0.22 ampere (A)

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#3 : Air Conditioning

Similarly, 

      P= V× I

3500=220×I

Therefore,  I= 15.90 ampere (A)

So from the above calculations, we are clear about the high consumption of current I.e electrical power by an AC boleto air conditioning. And this AC leads to a high rated bill each and every month.

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Now, 

guys, do you know that on which basis our the light bills are calculating by the municipality🤔. Yes, the answer is a kilowatt-hour (kWh). If you observe carefully the light bill attached below⤵

The high-lighted mark on the bill is nothing but a monthly unit which is used by the electrical appliances during the whole month of a house. So this unit is nothing but the amount of electrical energy consumed in a month.

Like if the unit is 150, then it means 150 kWh of electrical energy is consumed by all the electrical appliances of a house for one month. It means⤵

1unit = 1kWh

So kilowatt-hour is the unit of electrical energy which we used to pay in our electricity supply departments (Nagar Palika).  meter in our home is used to measure this electrical energy in terms of kilo-watt consumed by our home appliances.

So let’s have some real-life example to calculate the bill of a device so that you will get an idea of this kWh clearly.

Example: A television 📺 set is operated for 8 hours a day having a power rating of 50W. Calculate the cost of electrical energy consumed by this television 📺 set for 30 days (a month)at the rate of 7 Rs. Per kWh?

Ans ➡

My friend, first of all, we have to convert the power of 📺 as kilo-watt. So on dividing 50W by 1000 will get the answer in kilowatt.

Therefore power =  50÷1000

                           = 0.050 kW ———(1)

And now will calculate the time hours for 30 days.

Therefore time = 8×30 

                         = 240 h —————(2)

So the electrical energy consumed by this television set  📺 for a month will be, 

                      E = P  × t. ———–from eq. B

                          = 0.050 × 240 kWh

                          = 12 kWh 🤓 

So this is the electric Al energy consumed by the television 📺 set for a month.

This 12kWh is shown in the meter after 30 days as a unit. Now will calculate the cost of this 12 unit as per the given question.

Given is 7 Rs per kWh,  therefore for 12, units 

                       i.e 12×7 = 84 Rs.

So the cost consumption of television 📺set will be 84 Rs for 30 days.

similarly you can find the cost of each appliance in your home for same 30days and add them all to get your monthly bill of a home.

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