Light waves are an important part of electromagnetic radiation. They have several key features that help us understand how they behave and interact. These features include wavelength, frequency, amplitude, speed, and energy.

1. Wavelength and Frequency:

   • Wavelength is the distance between two peaks of a wave. It is measured in meters (m). For visible light, wavelengths go from about 400 nanometers (nm) for violet light to 700 nm for red light.
   • Frequency is how many wave cycles pass a point in one second. It's measured in hertz (Hz). Visible light has frequencies that range from about 7.5 x 10^14 Hz for red light to 4.3 x 10^14 Hz for violet light.
   • There’s a relationship between wavelength and frequency shown by this simple equation:
     • ( c = \lambda f )
     • Here, ( c ) is the speed of light, which is about 300 million meters per second (m/s).

2. Amplitude:

   • Amplitude is the maximum height of a wave from its resting position. In light waves, the amplitude is linked to how bright the light is. Larger amplitudes mean brighter light.

3. Speed of Light:

   • The speed of light in a vacuum is constant, around 300 million meters per second (m/s). This is often called ( c ).
   • In different materials, like air, water, or glass, light travels slower. This speed can be calculated using the refractive index ( n ) of the material:
     • ( v = \frac{c}{n} )
   • For example, in water (where ( n \approx 1.33 )), light travels at about 226 million m/s.

4. Energy:

   • Light carries energy, which can be measured using this formula:
     • ( E = hf )
     • Here, ( E ) is energy in joules (J), ( h ) is Planck's constant (approximately 6.626 x 10^-34 J·s), and ( f ) is the frequency. This means that light with a higher frequency, like ultraviolet light, has more energy than light with a lower frequency, like infrared light.

5. Electromagnetic Spectrum:

   • Light waves are part of the electromagnetic spectrum. This spectrum includes different types of electromagnetic radiation, ranging from radio waves (with the longest wavelengths) to gamma rays (with the shortest wavelengths).
   • Here are some categories in the spectrum:
     • Radio waves: longer than 1,000 meters
     • Microwaves: 1 mm to 1 m
     • Infrared: 700 nm to 1 mm
     • Visible light: 400 nm to 700 nm
     • Ultraviolet: 10 nm to 400 nm
     • X-rays: 0.01 nm to 10 nm
     • Gamma rays: shorter than 0.01 nm

Understanding these basic features helps us learn more about how light behaves. This knowledge leads to many useful applications in technology, healthcare, and communication.