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You have two identical capacitors and an external potential source. a) Compare the total energy stored in the capacitors when they ar
Question
You have two identical capacitors and an external potential source.
a) Compare the total energy stored in the capacitors when they are connected to the applied potential in series and in parallel.
U(parallel)/U(series) =?
b) Compare the maximum amount of charge stored in each case.
Q(parallel)/Q(series) =?
c) Energy storage in a capacitor can be limited by the maximum electric field between the plates. What is the ratio of the electric field for the series and parallel combinations?
E(parallel)/E(series) =?
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5 years
2021-08-23T05:47:38+00:00
2021-08-23T05:47:38+00:00 1 Answers
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Answer:
Explanation:
Given two identical capacitor
i.e they have the same capacitance C
Also let say we have external potential V
a. Now for series connection,
1/Ceq=1/C+1/C
1/Ceq=(1+1)/C
1/Ceq=2/C
Then, Ceq=C/2
Ceq=½C
So the energy stored in a capacitor is given as
Us= ½CeqV²
Us=½×½CV²
Us=¼CV²
Now, for parallel connection
Ceq=C+C
Ceq=2C
Then,
Energy is given as
Up=½CeqV²
Up=½×2CV²
Up=CV²
Comparing this to series
Us=¼CV², since CV²=Up
Then, Us=¼Up
Up=4Us
Up/Us=4
So the energy stored in the parallel capacitor connection is 4 times the energy stored in the series capacitor connection.
b. Charges
For series connection
We know that same charge pass through series connection. Now, for series the potential difference is V/2 since they have the same capacitance, they will share the voltage
And the charge is given as
Q=CeqV
Qs=½CV
Qs=½CV for each capacitor
Then the total charge will be
Qs=½CV×2.
Qs=CV
Now, for parallel connection
The have the same voltage but different charge,
The charge for parallel is given as
Q=CeqV
Qp=2CV
Now comparing
Qp/Qc=2CV / CV
Qp/Qc=2
The maximum charge of the parallel is four times that of the series again
c. Electric field is given as
E=V/d
The potential difference in parallel is V same voltage.
Ep=V/d
Now for series the potential difference is V/2 since they have the same capacitance, they will share the voltage
Es=V/2d.
Then,
Ep/Es=V/d ÷ V/2d
Ep/Es=V/d × 2d/V
Ep/Es=2