Technician License Course Lesson 3.1

Here’s your video introduction to Lesson 3.1 in the ARRL Ham Radio License Manual. Mea culpa: a verbal typo – I say that voltage flows from positive to negative. It’s current that does that, of course!
 

 
Hold the fort! I got a comment on YouTube “from Skylane Captain”:

Could you clarify the multiplication at 2:55 please……120 volts x .210 amps = 25.2 not 13. Thanks.

Here’s what I wrote in reply:

Thanks for the good catch. Indeed your math is correct. I should have caught that. The 13 watts comes from the fact that 0.21 amps is peak, not average (the bulb is not drawing a constant amount of power all the time). I don’t have an o-scope, so can’t check, but I suspect that it draws power only on the half cycle. If you have an o-scope, that would be an interesting thing to check out. It’s also possible that it draws 0.21 amps when starting, but settles back to a much lower amount – they have to list the maximum amperes it draws.

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