A filament bulb of 40 W and a LED bulb of 6 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.
A filament bulb of and a LED bulb of give about the same light. Each works hours a day for days. How many units does each use, and how many does the LED bulb save?
Need a reminder? The key ideaShow
Energy . One unit is : units power in kW time in hours. Cost units 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. Filament. .
Step 2. LED. .
Step 3. Saving. .
Answer: units and units; the LED saves units a month.
Check. The LED uses of the energy, so it saves .
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