1. An electromagnetic (EM) wave is a disturbance that propagates through space, carrying both electric and magnetic fields. It differs from other forms of waves, such as sound and water waves, in several ways:
- EM waves do not require a medium to propagate. Sound waves, for example, require a medium like air, water, or solids to travel through, whereas EM waves can travel through vacuum (empty space).
- EM waves travel at the speed of light, which is about 300,000 kilometers per second, whereas sound waves and water waves have much slower velocities.
- EM waves have a wide range of frequencies and wavelengths, whereas sound waves and water waves have specific frequencies and wavelengths associated with them.
2. The seven electromagnetic waves, in order of increasing frequency and decreasing wavelength, are:
- Radio Waves: Used in telecommunications for broadcasting and communication.
- Microwaves: Used in telecommunications, radar, and cooking.
- Infrared Waves: Used in heat imaging, remote controls, and communication.
- Visible Light: Enables us to see and is used in various lighting applications.
- Ultraviolet Waves: Used in sterilization, medicine, and forensic sciences.
- X-Rays: Used in medical imaging, security scanning, and material analysis.
- Gamma Rays: Used in medical treatments, cancer therapy, and nuclear research.
3. The electromagnetic spectrum is the range of all possible frequencies (or wavelengths) of electromagnetic radiation. It encompasses all seven types of electromagnetic waves mentioned above. The spectrum is divided into regions based on the different wavelengths and frequencies of the waves.
4. In terms of wavelength and frequency, the electromagnetic waves are arranged in a spectrum as follows:
- The spectrum starts with radio waves, which have the longest wavelength and lowest frequency.
- It progresses through microwaves, infrared, visible light (which is further divided into different colors ranging from red to violet), ultraviolet, X-rays, and finally, gamma rays.
- Gamma rays have the shortest wavelength and highest frequency in the spectrum.
5. Definitions:
a. Speed of a wave: It refers to how fast a wave propagates through a medium. In the case of electromagnetic waves, they travel at the speed of light, which is approximately 300,000 kilometers per second in a vacuum.
b. Frequency: It is the number of complete oscillations or cycles of a wave that occur per unit of time. It is measured in Hertz (Hz), which represents one cycle per second.
c. Wavelength: It is the distance between two consecutive peaks or troughs of a wave. It is usually represented by the Greek letter lambda (λ) and is measured in meters or other units of length.
