We usually define the wave's direction of vibration based on which field?

We usually define the wave's direction of vibration based on which field?

• A. Magnetic field
• B. Electric field
• C. Temperature gradient
• D. Pressure

Answer: (B)

The direction of a wave’s vibration, or its polarization, is defined by the oscillation of the electric field. In an electromagnetic wave, both the electric and magnetic fields oscillate as the wave travels, and they are perpendicular to each other and to the direction of propagation. But the orientation that we use to describe how the wave interacts with matter—how it polarizes, passes through polarizers, or excites dipoles in a material—is the electric field’s direction. The magnetic field accompanies the wave but isn’t the primary descriptor of the vibrational direction in standard optics. Temperature gradient and pressure aren’t involved in characterizing the wave’s oscillation.

The direction of a wave’s vibration, or its polarization, is defined by the oscillation of the electric field. In an electromagnetic wave, both the electric and magnetic fields oscillate as the wave travels, and they are perpendicular to each other and to the direction of propagation. But the orientation that we use to describe how the wave interacts with matter—how it polarizes, passes through polarizers, or excites dipoles in a material—is the electric field’s direction. The magnetic field accompanies the wave but isn’t the primary descriptor of the vibrational direction in standard optics. Temperature gradient and pressure aren’t involved in characterizing the wave’s oscillation.