Physics Circle home Student Login

Home›Chapters›Capacitors PYQs›Energy Stored & Force between Plates›Question 18

MHT CET 2023 (10 May, Shift 1) · Energy Stored & Force between Plates

Energy Stored & Force between Plates question from MHT CET 2023 (10 May, Shift 1)

Q18MHT CET 2023 · 10 MAY · SHIFT 1Medium

Energy Stored & Force between Plates

A parallel plate capacitor has plate area 'AA' and separation between plates is 'dd'. It is charged to a potential difference of V0V_0 volt. The charging battery is then disconnected and plates are pulled apart three times the initial distance. The work done to increase the distance between the plates is (ε0=(\varepsilon_0 = permittivity of free space)

Show answer and solution

Answer: (d)

  1. Battery disconnected: QQ constant, U=Q22CU = \frac{Q^2}{2C}.
  2. d→3d⇒C→C3d \to 3d \Rightarrow C \to \frac{C}{3}, so Uf=3UiU_f = 3U_i.
  3. W=2Ui=2×12ε0AdV02=ε0AV02dW = 2U_i = 2 \times \frac{1}{2}\frac{\varepsilon_0 A}{d}V_0^2 = \frac{\varepsilon_0 AV_0^2}{d}
  4. So the answer is (d) ε0AV02d\frac{\varepsilon_0 AV_0^2}{d}.
Report a mistake

More questions on Energy Stored & Force between Plates