KCET 2021 Physics Solved Paper

Let t be the thickness of the dielectric slab and K is the dielectric constant.
So, the increase in the distance of separation between the plates due to dielectric is given as
x=t−

t

K

=t(1−

1

k

)
Given, x=3.5×10−3m,t=4×10−3m
Substituting the given values in the above equation, we get
1−

1

k

=

x

t

=

3.5×10−3

4×10−3

=

3.5

4

or

1

k

=1−

3.5

4

=

0.5

4

or k=8