Consider the combination of two capacitors C_1 and C_2, with C_2>C_1, when connected in parallel, the equivalent capacitance is 10 times the…
JEE Main 2021 — Physics Electromagnetism
2021mcqhard
Consider the combination of two capacitors C1 and C2, with C2>C1, when connected in parallel, the equivalent capacitance is 10 times the equivalent capacitance of the same connected in series. Calculate the ratio of capacitors, C1C2.
Official previous-year question
Held on 26 Feb 2021 · Verified 6 Jul 2026.
Options
A
4+15
B
2+15
C
9
D
415
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Solution
When connected in parallel
Ceq=C1+C2
When in series
Ceq′=C1+C2C1C2
C1+C2=10(C1+C2C1C2)
(C1+C2)2=10C1C2
C12+C22−8C1C2=0
dividing by C12
(C1C2)2−C18C2+1=0
Let C1C2=x
x2−8x+1=0
x=28±64−4=4+15
This question was Bonus in JEE Main 2021 exam because of incorrect data in original question.
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