AP EAMCET201824 Apr 2018Morning ShiftPhysicsCapacitanceActual
The plates of a parallel plate capacitor are charged upto 100 ~V . A 2 ~mm thick insulator sheet is inserted between the plates. Then to maintain the same potential difference, the distance between the plates is increased by 1.6 ~mm . The dielectric constant of the insulator is
Options
- A6
- B8
- C5
- D4
Correct answer
C. 5
Step-by-step solution
Potential of capacitor before inserting insulator, V= d ₀ where, = surface charge density, d= distance between plates and ₀= permittivity of vacuum. Given, d ₀ =100 Now, potential after inserting 2 ~mm of insulator. Let its dielectric constant is k . aligned & V₁=E₁ 2+E₂(d-2) & V₁= ₀ k 2+ ₀ (d-2) V₁= ₀ ( 2 k +d-2 ) aligned To maintain potential difference, same distance is increased by 1.6 ~mm So, extra potential difference, V₂= ₀ (1.6) Clearly, V₁+V₂=V array lc & ₀ ( 2 k +d-2 )+ ₀ 1.6= d ₀ & d ₀ - 2 ₀ k - ₀ (d-2)=