Maxwell's Theory

Question 1

What are electromagnetic (EM) waves composed of?

Answer 1

Electromagnetic waves consist of alternating electric and magnetic fields that are:

• In phase with each other
• Oscillating at right angles to each other
• Both fields oscillate perpendicular to the direction of wave travel

Question 2

What is the relationship between the direction of oscillation of EM fields and wave travel?

Answer 2

The electric and magnetic fields oscillate perpendicularly to each other, and the wave travels in a direction perpendicular to both field oscillations.

Question 3

Who predicted the existence of electromagnetic waves and how?

Answer 3

James Clerk Maxwell predicted the existence of electromagnetic waves before experimental evidence was available. He developed a theoretical formula for the speed of EM waves in a vacuum.

Question 4

What is Maxwell’s formula for the speed of electromagnetic waves in a vacuum?

Answer 4

𝑐 = \frac{1}{\sqrt{\mu_0 \epsilon_0}}

Where:

• 𝑐 is the speed of light in a vacuum
• 𝜇₀ is the permeability of free space
• 𝜀₀ is the permittivity of free space

Question 5

What is the permeability of free space (μ₀) and what does it describe?

Answer 5

𝜇₀ relates the magnetic flux density produced by a wire to the current in that wire. It describes how magnetic fields interact with the vacuum.

Question 6

What is the permittivity of free space (ε₀) and what does it describe?

Answer 6

𝜀₀ relates the electric field strength to the charge on the object creating the field. It describes how electric fields interact with the vacuum.