Today classes got to experiment with some simple DC circuits and tiny incandescent Christmas light bulbs, after discussing how we pay for electricity (kilowatt - hours (kWh)) and finding out how to go from knowing an appliance's wattage to finding how much we pay at about 10 cents per kWh.
Some other announcements:
Mrs. Greene will visit Thursday to give out answers to algebra review quizzes (you and parents register for classes Thursday night (Connect?))
The bonus problem in the notes: what happens to an appliance's power when you double its voltage, as if you took a 120V appliance (U.S.A.) to another country outside North America?
Current within it doubles, and since current is then multiplied by double the voltage, the power of the device quadruples!!!
This is why electric lines transmitting huge amounts of electricity use higher voltage - resistance becomes insignificant as voltage is increased, because a huge amount of current is not needed to deliver lots of energy as long as that energy is at a high potential (voltage).
This is also why the rest of the world operates at a much more efficient 120V, and why we in the U.S.A. don't just use an even lower voltage (like 12V or less) to deliver energy to our homes. It would be safe for anyone to touch, but resistance would be a huge factor and make any significant transmission distance impossible.
Optional assignment that was assigned on Friday is due Jan 25th. See Friday's post.
HMWK for Tuesday: see Friday's post.
No comments:
Post a Comment