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Unformatted text preview: Light Bulb Problems Light bulb problems have become extremely common on many standardized tests. For the most part, these problems can be solved like any other resistive circuit problem, treating the light bulbs as resistors. Usually, the problems involve multiple identical bulbs, so you can pretend they are all 1-ohm resistors to simplify things. For identical bulbs, the one having the highest voltage or highest current will be brightest. The circuit below contains four identical light bulbs labeled A, B, C, and D. Which one will be brightest? Pretend every bulb is 1 Ω . At this point, you’re probably familiar enough with Kirchhoff’s Voltage Law that you don’t even need to draw the current loops. Starting from the lower left corner, the first equation is -10+I ₁ +(I ₁ +I ₂ )=0 . Then from the lower right, the second equation is I ₂ +I ₂ +(I ₁ +I ₂ )=0 . Simplifying, the equations become 2I ₁ +I ₂ =10 and I ₁ +3I ₂ =0 . You should be able to solve these to get...
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This note was uploaded on 04/05/2012 for the course PHYS 131 taught by Professor Tibbets during the Spring '11 term at Cuyamaca College.
- Spring '11