Find the dielectric constant of the medium?

AI Thread Summary
The problem involves calculating the dielectric constant of a medium based on the forces exerted by two point charges in free space and in a dielectric medium. The force in free space is given as 1.4 x 10^-4 N, while in the dielectric medium, it is 0.9 x 10^-4 N. The relationship between the forces in free space and the medium can be expressed through the dielectric constant, where the force in the medium is reduced by the factor of the dielectric constant. The key equation to use is the comparison of the two forces, leading to the conclusion that the dielectric constant can be derived from the ratio of these forces. The discussion emphasizes understanding the relationship between electrostatic forces in different environments to solve for the dielectric constant.
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Homework Statement


Two point charges a distance d apart in free space exert a force of 1.4∗10^−4 [N]. When the free space is replaced by a homogeneous dielectric medium, the force become .9∗10^−4 [N]. What is the dielectric constant ϵr of the medium?


Homework Equations


E=F/Q


The Attempt at a Solution


I have been staring at this problem for awhile. I can only think of using E=F/Q. But the problem is this only applies to free space and I do not know Q. So I am not sure where to start to compare the free space and medium.
 
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The coulombic force in free space is k.q1.q2/r^2. In a medium, the value of k changes to k/dielectric constant. Now try to solve the question. :D
Hint : Compare the 2 values of electrostatic force.
 
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