How Does Introducing Different Dielectrics Affect Capacitance?

[vijayramakrishnan]

Homework Statement

A parallel plate capacitor having plates of area S and plate separation d, has capacitance C1 in air. When two dielectrics of different relative permittivities ( ε₁=2 and ε₂=4) are introduced between the two plates as shown in the figure, the capacitance becomes C2. the ratio C₂/C₁ is

Homework Equations

C= ε₀A/d[/B]

The Attempt at a Solution

if we name the components 1,2,3,4 in clockwise manner,in the solution 1 and 2 are taken in series and 3 and 4 are taken in series and they both are connected parallel,can we also take 1 and 4 in parallel and 2 and 3 in parallel and they both are connected in series?in that case answer comes out to be 12/5 where have i gone wrong?
[/B]

 

[cnh1995]

can we also take 1 and 4 in parallel and 2 and 3 in parallel and they both are connected in series?

No. Electric field between 1 and 2 (left half) is not same as the electric field between 3 and 4(left half).

 

[vijayramakrishnan]

No. Electric field between 1 and 2 (left half) is not same as the electric field between 3 and 4(left half).

sir 2 is not left half,1234 in clockwise direction

 

[vijayramakrishnan]

sir 2 is not left half,1234 in clockwise direction

sir,do you mean to say that the potential difference between positive terminal and interface between 1 and 2 is not same as potential difference between positive terminal and interface between 3 and 4.

 

[vijayramakrishnan]

No. Electric field between 1 and 2 (left half) is not same as the electric field between 3 and 4(left half).

sir,do you mean to say that the potential difference between positive terminal and interface between 1 and 2 is not same as potential difference between positive terminal and interface between 3 and 4.