jimmy42 said:Hi,
In my physics book I have two values for the permittivity of free space:
8.854x10^-12 c^2 N^-1 m^-2
and
8.988x10^9 N m^2 C^-2
What is the difference between these two? When would I use one or the other?
Thanks.
That's the permittivity of free space, usually symbolized as ε0.jimmy42 said:In my physics book I have two values for the permittivity of free space:
8.854x10^-12 c^2 N^-1 m^-2
That's Coulomb's constant, usually symbolized as k. (Not the permittivity of free space!)and
8.988x10^9 N m^2 C^-2
They are related by: k = 1/4πε0.What is the difference between these two? When would I use one or the other?
The permittivity of free space, also known as the electric constant, is a physical constant that represents the ability of a vacuum to permit the movement of electric fields. It is denoted by the symbol ε0 and has a value of approximately 8.85 x 10^-12 farads per meter (F/m).
Coulomb's law, which describes the force between two point charges, includes the permittivity of free space in its equation. This constant acts as a proportionality factor between the electric force and the distance between the charges, and it is used to calculate the strength of the electric field between the charges.
The SI unit of permittivity of free space is farads per meter (F/m). However, it is also commonly expressed in other units such as coulombs squared per newton-meter squared (C^2/Nm^2) or ampere squared per joule-meter (A^2/Jm).
Permittivity of free space can be measured using various techniques, such as capacitance measurements, interferometry, and microwave cavity resonators. These methods involve measuring the electric field or displacement in a vacuum and calculating the permittivity based on its relationship with other physical quantities.
The permittivity of free space is a fundamental constant in electromagnetism and is used in many equations and theories to describe the behavior of electric fields. It is also important in practical applications, such as the design of electronic devices, transmission of radio waves, and calculation of capacitance in circuits.