What is the dielectric constant of air?

What is the dielectric constant of air?

• A. 0
• B. 1
• C. 2
• D. 10

Answer: (B)

The dielectric constant, or relative permittivity, tells you how much a medium reduces an applied electric field compared with vacuum. Air is extremely close to vacuum in this respect, so its dielectric constant is essentially 1 (the precise value is about 1.0006, but we approximate as 1 for practical calculations). Values near 1 indicate very little polarization of the medium in an electric field, which is why air behaves almost like empty space in electrical problems. The numbers 0 or much higher than 1 don’t match air’s weak polarization: 0 would imply no ability to support an electric field, which isn’t physically plausible for a real medium, and numbers like 2 or 10 would indicate much stronger polarization than air.

The dielectric constant, or relative permittivity, tells you how much a medium reduces an applied electric field compared with vacuum. Air is extremely close to vacuum in this respect, so its dielectric constant is essentially 1 (the precise value is about 1.0006, but we approximate as 1 for practical calculations). Values near 1 indicate very little polarization of the medium in an electric field, which is why air behaves almost like empty space in electrical problems. The numbers 0 or much higher than 1 don’t match air’s weak polarization: 0 would imply no ability to support an electric field, which isn’t physically plausible for a real medium, and numbers like 2 or 10 would indicate much stronger polarization than air.