Q.

Consider two infinitely large plane parallel conducting plates as shown below. The plates are uniformly charged with a surface charge density +σ and 2σ. The force experienced by a point charge +q placed at the midpoint between two plates will be:          [2025]

1 σq4ε0  
2 3σq2ε0  
3 3σq4ε0  
4 σq2ε0  

Ans.

(2)

Final charge distribution on different surfaces,

Electric field between the plates,

E=E1+E2=(32σ)2ε0+(32σ)2ε0=3σ2ε0

 F=Eq=3σq2ε0