Rankers Physics
Topic: Capacitors
Subtopic: Parallel Plate Capacitor

Ten capacitors are joined in parallel and charged with a battery up to a potential V. They are then disconnected from the battery and joined in series. Then, the potential of this combination will be:
1 V
10 V
5 V
2 V

Solution:

Let's analyze the problem step by step and derive why the potential difference is 10 V.


1. Capacitors in Parallel (Initial Condition)

When the 10 capacitors, each with capacitance

CC

, are connected in parallel:

  • The equivalent capacitance is:
    Cparallel=10CC_{\text{parallel}} = 10C
     
  • The total charge stored when connected to a battery of potential
    VV
     

    is: Q=CparallelV=(10C)V=10CVQ = C_{\text{parallel}} \cdot V = (10C) \cdot V = 10CV 


2. Capacitors in Series (Reconfigured System)

After disconnecting the battery, the capacitors are joined in series:

  • The equivalent capacitance for 10 capacitors in series is:
    Cseries=C10C_{\text{series}} = \frac{C}{10}
     
  • The charge
    QQ
     

    stored on the series combination remains the same (as charge is conserved): Qseries=Q=10CVQ_{\text{series}} = Q = 10CV 


3. Potential Across the Series Combination

The potential difference across a capacitor or combination of capacitors is related to the charge

QQ

and capacitance

CC

:

 

Vseries=QCseriesV_{\text{series}} = \frac{Q}{C_{\text{series}}}

 

Substitute

Q=10CVQ = 10CV

and

Cseries=C10C_{\text{series}} = \frac{C}{10}

:

 

Vseries=10CVC10=VV_{\text{series}} = \frac{10CV}{\frac{C}{10}} = V

 

Thus, the potential across the series combination is

V=10VV = 10V

,.


Final Answer:

The potential of the series combination is:

 

10V\boxed{10V}

 

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