Three capacitors are connected in SERIES. One has a capacitance of 9.0uF and another has a capacitance of 6.3μF . If the total capacitance is 2.1uF what is the capacitance of the third capacitor?
8.5uF
4.1uF
7.1uF
4.8uF
peterpan
Favorite Answer
1 / C = 1 / C1 + 1 / C2 + 1 / C3
1 / C3 = 1 / C - 1 / C1 - 1 / C2
1 / C3 = (C1 C2 - C2 C - C1 C) / (C C1 C2)
C3 = (C C1 C2) / (C1 C2 - C2 C - C1 C)
C3 = (2,1*9*6.3) / (9*6.3 - 6.3*2.1 - 9*2.1) ~ 4,8 μF
Morningfox
I get 4.85 uF, because 1/9.0 + 1/ 6.3 + 1/4.85 = 1/ 2.1
With the precision of the numbers in the problem, the answer could be anything in the range 4.59 to 5.12 uF.