Talking to candidates for the post of science teachers in high schools, a few times I asked “what would be the cost of electricity when you iron your cotton saree?”
Even those with more than 5 years of experience in teaching physics, give blank looks. I give them an old electricity bill and then ask to calculate; but still see them lost. Such questions are not in the text books, and not discussed in classrooms. “What input do you need? What assumptions would you make?” No, they do not want to think about these issues as such questions do not appear in examinations.
However, let us give it a try.
From a sample electricity bill we have the following information:
|Rate per KWH, Rs.||Consumption
|0 – 30||2.10||30||63.00|
|31 – 100||3.20||70||224.00|
|101 – 200||4.20||100||420.00|
Total Bill Amount = Rs. 1020.60
Consider that it takes 15 minutes to iron a saree and the wattage of the iron is 1KW. Then, the electricity consumption is ¼ KWH. What I would have spent on electricity depends on the range at which I consumed (approximate):
|0 – 30||31 – 100||101 – 200||>200|
|Rate + tax + fixed charge per KWH Rs.||2.40||3.60||4.80||5.60|
Now, we have touched some lessons from the chapter on electricity and some lessons on arithmetic.
With the above breakdown, what I spend on ironing the saree depends on the priorities in my view. If it is the most important task, even more than lighting, then I would consider the cost to be 63 paise. If the task was the least important, then the cost is Rs. 1.40. If the task is least important, the cost would vary based on the total consumption. If my total consumption was less than 200 KWH, then I would have paid Rs. 1.20 and if it was less than 100 KWH, I would pay 90 paise.
The more you consume, higher is the rate we pay. This is a lesson in social science and general knowledge!
We have an opportunity to know the rating of different gadgets we use at home – look at TV, refrigerator, geyser, lamps, fan …
Consumer products advertise, buy one and get one free. The more we buy the more discounts we get. In electricity, water and BSNL telephone bills, the more we consume, the higher the rate. This is an effort from the government
- To reduce the consumption of scarce resources.
- Collect more from those who consume more and subsidise those who consume less.
- At higher range of consumption, the rate at which we can reduce or increase the electricity bill is higher. Every few extra minute we leave the geyser on, or neglect to turn off another gadget when not in use, the higher penalty we pay. Such neglect can move us up the penalty band – from Rs. 2.40 to Rs. 5.60 per KWH. Ration of cost of electricity from the lowest to the highest range is 3:7
These rates are for domestic connections. For commercial connections, it is Rs. per KWH.
If we teach our children these little facts, they may see different light in the electricity bill. No bill is an island. Each one is an opportunity to reflect and discuss.