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NEET
Exam
NEET
Subject
Physics
Chapter
Capacitance

NEET · Physics · Capacitance

Given below are two statements: one is labelled as Assertion (A)...

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A): When two identical capacitors are connected in series across a battery, the total energy stored in the combination is twice the energy that would be stored in a single such capacitor connected across the same battery.
Reason (R): In a series combination, the equivalent capacitance decreases, and for a given voltage source, the total energy stored is directly proportional to the equivalent capacitance.

In the light of the above statements, choose the most appropriate answer from the options given below:

Options

  1. ABoth (A) and (R) are true and (R) is the correct explanation of (A)
  2. BBoth (A) and (R) are true but (R) is not the correct explanation of (A)
  3. C(A) is true but (R) is false
  4. D(A) is false but (R) is true

Correct answer

D. (A) is false but (R) is true

Step-by-step solution

For a single capacitor of capacitance CC connected across a battery of voltage VV, the energy stored is U0=12CV2U_0 = \dfrac{1}{2}CV^2.

When two such identical capacitors are connected in series, the equivalent capacitance becomes Ceq=C2C_{eq} = \dfrac{C}{2}.

The total energy stored in the series combination across the same battery is Useries=12CeqV2=12(C2)V2=12U0U_{series} = \dfrac{1}{2}C_{eq}V^2 = \dfrac{1}{2}\left(\dfrac{C}{2}\right)V^2 = \dfrac{1}{2} U_0. Thus, the total energy is halved, not doubled. Therefore, the Assertion (A) is false.

The energy stored for a given voltage source is U=12CeqV2U = \dfrac{1}{2}C_{eq}V^2. Since VV is constant, U∝CeqU \propto C_{eq}. In a series combination, CeqC_{eq} decreases, which directly leads to a decrease in the total energy stored. Therefore, the Reason (R) is true.

Hence, (A) is false but (R) is true.

Answer: (A) is false but (R) is true
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