Answer
405.3k+ views
Hint:To find the energy stored in any capacitor, we need to know the value of the capacitance of the capacitor and the potential difference across its plates. We have been given the potential difference across the entire setup of capacitors but we need to find the energy stored only in the capacitor \[{C_2}\] , so firstly, we need to find the potential difference across \[{C_2}\] and then proceed as follows.
Complete step-by-step solution:
Firstly, resolve the given system of capacitors into a single capacitor by finding the equivalent capacitance of the system.
\[\dfrac{1}{{{C_{eq}}}} = \dfrac{1}{{{C_1}}} + \dfrac{1}{{{C_2}}} + \dfrac{1}{{{C_3}}}\]
\[\therefore \dfrac{1}{{{C_{eq}}}} = \dfrac{1}{{20}} + \dfrac{1}{{30}} + \dfrac{1}{{15}}\] \[ \Rightarrow \dfrac{1}{{{C_{eq}}}} = \dfrac{9}{{60}} \Rightarrow {C_{eq}} = 6.67\mu F\]
This means that charge flowing through the circuit \[Q = {C_{eq}}V = 6.67\mu F \times 90V = 600\mu C\]
Now let’s consider our capacitor \[{C_2}\] ,
The charge flowing through this capacitor will be the same as charge flowing through the setup of capacitors, hence \[Q = {C_2}{V_{_2}} \Rightarrow {V_{_2}} = \dfrac{Q}{{{C_2}}} = \dfrac{{600}}{{30}} = 20V\]
Now we know the potential difference across \[{C_2}\] and its capacitance, so we can easily find the energy stored in it.
Energy of the capacitor $(E) = \dfrac{1}{2}C{V^2}$
By substituting the values in the formula, we get
\[{E_2} = \dfrac{1}{2}{C_2}{V_{_2}}^2 = \dfrac{1}{2} \times 30\mu F \times {(20V)^2} = 6 \times {10^{ - 3}}J\]
Additional Information:
For solving questions having a combination of capacitors or resistors, we need to find the physical quantity that remains the same throughout the entire system, for example, in a series combination of capacitors, charge flowing through the circuit remains the same. Similarly, for a series combination of resistors, the current through the circuit remains constant and for a parallel combination, the potential difference across each component remains the same. Once we have found the constant quantity, we can easily divide current, potential, charge or energy among the individual components.
Note:- One common error made by students is that while calculating energy, they use the equivalent capacitance of the circuit instead of the capacitance of the specific capacitor whose energy is to be calculated. Make sure not to make that error.
Complete step-by-step solution:
Firstly, resolve the given system of capacitors into a single capacitor by finding the equivalent capacitance of the system.
\[\dfrac{1}{{{C_{eq}}}} = \dfrac{1}{{{C_1}}} + \dfrac{1}{{{C_2}}} + \dfrac{1}{{{C_3}}}\]
\[\therefore \dfrac{1}{{{C_{eq}}}} = \dfrac{1}{{20}} + \dfrac{1}{{30}} + \dfrac{1}{{15}}\] \[ \Rightarrow \dfrac{1}{{{C_{eq}}}} = \dfrac{9}{{60}} \Rightarrow {C_{eq}} = 6.67\mu F\]
This means that charge flowing through the circuit \[Q = {C_{eq}}V = 6.67\mu F \times 90V = 600\mu C\]
Now let’s consider our capacitor \[{C_2}\] ,
The charge flowing through this capacitor will be the same as charge flowing through the setup of capacitors, hence \[Q = {C_2}{V_{_2}} \Rightarrow {V_{_2}} = \dfrac{Q}{{{C_2}}} = \dfrac{{600}}{{30}} = 20V\]
Now we know the potential difference across \[{C_2}\] and its capacitance, so we can easily find the energy stored in it.
Energy of the capacitor $(E) = \dfrac{1}{2}C{V^2}$
By substituting the values in the formula, we get
\[{E_2} = \dfrac{1}{2}{C_2}{V_{_2}}^2 = \dfrac{1}{2} \times 30\mu F \times {(20V)^2} = 6 \times {10^{ - 3}}J\]
Additional Information:
For solving questions having a combination of capacitors or resistors, we need to find the physical quantity that remains the same throughout the entire system, for example, in a series combination of capacitors, charge flowing through the circuit remains the same. Similarly, for a series combination of resistors, the current through the circuit remains constant and for a parallel combination, the potential difference across each component remains the same. Once we have found the constant quantity, we can easily divide current, potential, charge or energy among the individual components.
Note:- One common error made by students is that while calculating energy, they use the equivalent capacitance of the circuit instead of the capacitance of the specific capacitor whose energy is to be calculated. Make sure not to make that error.
Recently Updated Pages
Draw a labelled diagram of DC motor class 10 physics CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
A rod flies with constant velocity past a mark which class 10 physics CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Why are spaceships provided with heat shields class 10 physics CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
What is reflection Write the laws of reflection class 10 physics CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
What is the magnetic energy density in terms of standard class 10 physics CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Write any two differences between a binocular and a class 10 physics CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Trending doubts
Difference Between Plant Cell and Animal Cell
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Give 10 examples for herbs , shrubs , climbers , creepers
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Fill the blanks with the suitable prepositions 1 The class 9 english CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Name 10 Living and Non living things class 9 biology CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Change the following sentences into negative and interrogative class 10 english CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Fill the blanks with proper collective nouns 1 A of class 10 english CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Select the word that is correctly spelled a Twelveth class 10 english CBSE
![arrow-right](/cdn/images/seo-templates/arrow-right.png)
Write the 6 fundamental rights of India and explain in detail
![arrow-right](/cdn/images/seo-templates/arrow-right.png)