An electromagnetic wave and a light wave are essentially the same thing, as light is a specific type of electromagnetic wave. However, the distinction between the two terms is often based on context and usage.
Electromagnetic Wave: An electromagnetic wave refers to a broad category of waves that encompass a wide range of frequencies and wavelengths. Electromagnetic waves include not only visible light but also other forms of electromagnetic radiation such as radio waves, microwaves, infrared radiation, ultraviolet radiation, X-rays, and gamma rays. They all share common properties and are characterized by the oscillating electric and magnetic fields perpendicular to each other and to the direction of wave propagation.
Light Wave: Light specifically refers to the subset of electromagnetic waves that fall within the visible spectrum, the range of wavelengths that are detectable by the human eye. Visible light occupies a small portion of the overall electromagnetic spectrum, ranging approximately from 400 to 700 nanometers in wavelength.
So, the key difference between an electromagnetic wave and a light wave lies in the specific range of wavelengths being considered. Electromagnetic waves encompass a broader range of frequencies and wavelengths, while light waves specifically refer to the subset of electromagnetic waves within the visible spectrum.
The difference in perception and terminology arises from how humans interact with and perceive electromagnetic waves. Our eyes are sensitive to the particular range of wavelengths within the electromagnetic spectrum that we define as visible light. The rest of the electromagnetic spectrum, which includes other frequencies and wavelengths, cannot be detected by the human eye without the use of specialized instruments.
In summary, while all light waves are electromagnetic waves, not all electromagnetic waves are considered light waves. The distinction lies in the specific range of wavelengths and the human perception of light within that range.