If the air medium between two charges Is replaced by water the electro static force is
Answers
We will have to assume that the potential difference between the plates remains unchanged.
The force of attraction will get graeter. Air is unpolarised. Water consists of polar molecules. The water molecules will allign with the oxygen (negative bit) closer to the positive plate. The hydrogens will tend to point towards the enegative plate ( the hydrogens are slightly positive). The net effect is that each plate sees the presence of an opposite charge to be closer when the water is present because the plate is responding to the charges in the water not just the opposite plate.
This could be explained by talking about dielectrics, but I supect that is unlikely to be understood and might be regarded as just names so I have tried to explain the mechanism.
Explanation:
let initial force be F then as per the second case water is introduced having a dielectric constant of 80 so resultant force becomes F/80