An old bulb of 75 W and an LED bulb of 11 W give about the same light…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
An old bulb of and an LED bulb of give about the same light. Each burns for every day for days. Find
- the energy each one uses, in kWh;
- the energy saved by the LED;
- the money saved, if one unit costs ₹.
Need a reminder? The key ideaShow
, and one unit on a bill is one kWh. Units power in kW time in hours; cost units the price of one unit.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) Old bulb. .
Step 2. (a) LED. .
Step 3. (b) .
Step 4. (c) ₹ ₹.
Answer: and units; units saved, about ₹ a month.
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