Posted by fatih on Thursday, February 16, 2012 at 9:51pm.
two unknown resistors a and b are connected together. when they are connected in series their combined resistance is 15 ohm. When they are connected in parallel, their combined resistance is 3.3 ohm. What are the resistances of A and B?

physics  Henry, Thursday, May 28, 2015 at 8:28pm
R1+R2 = 15 Ohms
R1*R2/(R1+R2) = 3.3 Ohms
In Eq2, replace R1+R2 with 15 Ohms:
R1*R2/(15) = 3.3
R1*R2 = 49.5
R1 = 49.5/R2
In Eq1, Replace R1 with 49.5/R2:
(49.5/R2)+R2 = 15
R2^2 + 49.5 = 15R2
R2^2  15R2 + 49.5 = 0
Use Quad. Formula:
R2 = 10.1 Ohms
R1 + 10.1 = 15
R1 = 4.9 Ohms
Answer This Question
Related Questions
 physics (please check)  A total resistance of 3 ohms is to be producd by ...
 Gupta  When Two Resistors Are Joined In Series , The Equivalent Resistance Is ...
 physix  three resistances of value 1 ohm, 2 ohm and 3 ohm are connected in ...
 Physics  Two resistors connected in series have an equivalent resistance of 783...
 physics  ten identical resistors connected in parallel have an equivalent ...
 Physics  Thanks for any help :) Four 20 ohm resistors are connected in parallel...
 physics  the effective resistacce of two resistors connected in series is 100 ...
 Physics  What is the equivalent resistance of two resistors of 2 ohm and 3 ohm ...
 science  Three different resistors: 10 ohm, 20 ohm, and 20 ohm are connected in...
 Physics  Two resistors of 2.0 ohm and 3.0 ohm are connected a) in series b) in ...
More Related Questions