Although all electromagnetic radiations travel at the same velocity, how do they differ?

• A. In intensity and charge
• B. In wavelength and frequency
• C. In temperature and pressure
• D. In amplitude and phase

Answer: (B)

Electromagnetic radiations are characterized by their wavelength and frequency. While all forms of electromagnetic radiation, such as radio waves, microwaves, visible light, X-rays, and gamma rays, travel at the speed of light in a vacuum, they differ significantly in their wavelength and frequency.

Wavelength refers to the distance between successive peaks of a wave, and frequency describes the number of wave cycles that pass a point in one second. These two properties are inversely related: as the wavelength increases, the frequency decreases, and vice versa. This relationship is described by the formula:

[ \text{Speed} = \text{Wavelength} \times \text{Frequency} ]

Because of this relationship, different types of electromagnetic radiation can be classified on the electromagnetic spectrum. For instance, radio waves have long wavelengths and low frequencies, while gamma rays have very short wavelengths and high frequencies. Consequently, the energy of electromagnetic radiation is also directly related to frequency; higher frequency radiation carries more energy.

In summary, the difference in wavelength and frequency is essential for differentiating between various forms of electromagnetic radiation and understanding their properties and interactions with matter.