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5F20.u1 - Resistance Light Board

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​5F20.u1 - Resistance Light Board

Title5F20.u1 - Resistance Light Board

Demonstrate how different power light bulbs behave in series and in parallel.

Assembly Instructions

There is a board built as shown above. Connect to 110-V AC and start with equal bulbs on the left and right, say two 25-watt bulbs on the left and two 100-watt bulbs on the right. Note that the 25-watt bulbs burn brighter than the 100-watt bulbs since they have 2/5 of the voltage across them. Place a shorting wire across AB and note that there is no change. With this shorting wire in place, short out one of the bulbs and note the result. Repeat the same procedure with the wire AB removed.

Note that if it is necessary to replace one of the bulbs it may be necessary to replace the other bulb of the same size in order to keep them matched.

Note: Relative brightness is not a good measure of power in all cases here.  It doesn't always come out the way it should.  Probably due to change of R with temperature

Setup Time5
Operation Time
Preview Time10
Operation Instructions
Demo on DimeNo
PIRA 200No
Export Instructions (if different)
Category5 Electricity and Magnetism
Subcategory5F - DC Circuits
Keywordsresistance, series, parallel, electrical short
Construction Information
resistance light board
light bulb - 100W
light bulb - 25W
banana to AC line plug adapter
banana cable
(optional) light bulbs - 40W and 60W