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MHT CET 2025 (20 Apr, Shift 2) · Electric Flux & Gauss's Law

Electric Flux & Gauss's Law question from MHT CET 2025 (20 Apr, Shift 2)

Q21MHT CET 2025 · 20 APR · SHIFT 2Easy

Electric Flux & Gauss's Law

A hollow cylinder has a charge ' qq ' coulomb within it. If ' ϕ\phi ' is the electric flux in unit of V-m associated with the curved surface C, the flux linked with the plane surface ' AA ' in unit of V-m will be [ ε0=\varepsilon_0 = permittivity of free space]0

Figure

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Answer: (c)

  1. Total flux through the closed cylinder: ϕA+ϕB+ϕC=qε0\phi_A + \phi_B + \phi_C = \dfrac{q}{\varepsilon_0}.
  2. With the charge at the centre, the two flat faces get equal flux: ϕA=ϕB\phi_A = \phi_B, and ϕC=ϕ\phi_C = \phi.
  3. 2ϕA=qε0−ϕ⇒ϕA=12(qε0−ϕ)2\phi_A = \dfrac{q}{\varepsilon_0} - \phi \Rightarrow \phi_A = \dfrac{1}{2}\left(\dfrac{q}{\varepsilon_0} - \phi\right)
  4. So the answer is (c).
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