SOLUTION: Two electrical resistors are connected in parallel. The resistance of one of them is 15 ohms and the resistance of the combination is 5 ohms. What is the resistance of the other re

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Question 970063: Two electrical resistors are connected in parallel. The resistance of one of them is 15 ohms and the resistance of the combination is 5 ohms. What is the resistance of the other resistor?
1 1 1
-= - + -
r r^1 r^2
Found 2 solutions by macston, Alan3354:
Answer by macston(5194) About Me  (Show Source):
You can put this solution on YOUR website!
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R%5BT%5D=Total resistance; R%5B1%5D=value of resistor 1; r%5B2%5D=value of resistor 2
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1%2FR%5BT%5D=1%2FR%5B1%5D%2B1%2FR%5B2%5D
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1%2FR%5BT%5D-1%2FR%5B1%5D=1%2FR%5B2%5D Plug in values
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1%2F5ohms-1%2F15ohms=1%2FR%5B2%5D
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2%2F15ohms=1%2FR%5B2%5D Cross multiply.
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2R%5B2%5D=15ohms Divide each side by 2.
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R%5B2%5D=7.5ohms
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ANSWER: The other resistor is 7.5 ohms.

Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
15R/(15+R) = 5
R = 7.5 ohms