Question

What is the SI unit of relative permitivity?​

Answer 1

Explanation:

Relative permittivity e(r) is defined as the ratio of absolute permittivity of a medium (e) to the absolute permittivity of free space (e0)

e(r) = e / e0

It can also be defined as the the ratio of forces of attraction/repulsion between two point charges separated by a certain distance in vacuum to the force of attraction when they are placed in a medium same distance apart.

e(r) = F(o) / F(medium)

Clearly relative permittivity is a unitless constant.

Force between two charges is maximum when they are placed in vacuum.

In your second part, force in vacuum should be 100 N and that in medium be 10 N

such that relative permittivity = 100 / 10 = 10

Answer 2

The SI unit of relative permittivity is Farad Per Metre

• "Relative permittivity is the property of the material that affects the Coulomb force between two point charges in the material"

• Because of this relative permittivity the electric field between the charges is decreased.
• It is decreased relative to vacuum
• This unit is commonly used in System International unit system

• The dimension of Farad per meter is $M^{-1}$$L^{-3}$$T^{4}$$I^{2}$ where M is the Mass l is the length T is the Time and I is the Current

• Farad per meter is also represented as F/m or F ×$m^{-1}$