Introduction
Communicating scientific concepts to the public is a tough problem. One of the major issues is that people have a difficult time imagining the relative scale of things -- just try to think of 1000 of something versus 10 of the same thing. You cannot really visualize 1000 of something.
I normally try to work by analogy. This means comparing an unknown thing to something that is very familiar. Astronomers do this all the time. Here is an example from an astronomy article I read today about a distant supernova called Mingus. To convey a sense of how dim this supernova is, an analogy using a firefly's light was used:
Mingus was so distant and so faint — the equivalent of looking at a firefly from 3,000 miles (5,000 kilometers) away — that its true nature remained a mystery for a while, researchers said.
People can at least try to imagine how bright a firefly is and how it might look from 3000 miles away -- even though you really cannot imagine something that like.
On a less dramatic scale, I was asked if I could compare the yearly operating cost of one of our products (an Optical Network Terminal [ONT]) to that of a common electrical device -- a 100 W incandescent light bulb. I thought it would be useful run through how I answered that request.
Background
The basic facts of the analysis are straight forward and are listed here:
- An ONT draws 8 W of power on average from a 12 V power adapter.
- The 12 V power adapter has a typical efficiency of 80%.
- A kilowatt-hour of electrical power costs $0.1076 in Minnesota (my home state).
- A 100 W incandescent light bulb uses 100 W -- I know this seems obvious, but I felt I had to say it.
Our salesman a couple of simple pieces of information about ONT power usage that customers will remember:
- How much does it cost to power an ONT for a year?
- How does that cost compare to the cost of powering a 100 W lightbulb for some period of time?
Analysis
Figure 1 shows my calculations to estimate the values requested by our salesmen. I decided to provide the answers in the following form:
- Cost of running an ONT for a year in Minnesota.
- Cost of 1 year of ONT operation versus operating time for equivalent cost of operating a 100 W light bulb.
- Cost of 1 month of ONT operation versus operating time for equivalent cost of operating a 100 W light bulb.
Figure 1 shows how I computed the answers. Since an ONT draws 10 W from the outlet, the 100 W light bulb draws power at ten times the rate of an ONT.
Figure 1:Calculations for ONT Annual Operating Cost.
- Cost of running an ONT for a year in Minnesota = $9.43.
- Cost of 1 year of ONT operation equals that of a 100 W light bulb running for 5 weeks.
- Cost of 1 month of ONT operation equals that of a 100 W light bulb running for 3 days.
Conclusion
This was a simple calculation example, but it represents the kind of math that is routinely done to assist customers with understanding our products.