Light is a fundamental part of physics and has some very interesting properties.

• Light travels in a straight line in a uniform space because a straight line is the most direct path.Fermat's Principle of Least Time principle states That when light travels between two points, it follows the path that takes the shortest amount of time. It only changes direction when it interacts with a new substance, such as when it reflects off a mirror.

• We see our images in a mirror because of specular reflection.

  • A mirror's perfectly smooth surface reflects all parallel light rays at the same angle.

  • Our brain traces these reflected rays back, creating a virtual image behind the mirror.

• Light is not a state of matter.

  • Matter has mass and volume.

    • Light is a form of energy made of massless particles called photons.

  • Light has both wave and particle properties, a concept called wave-particle duality.

     - When light is traveling, it acts like a wave. It can bend around objects and interfere with itself, just like waves in water.

     - When light hits something, it acts like a particle (a tiny packet of energy called a photon). For example, when light hits a solar panel, it's the photons hitting the panel that create electricity.An object appears black because it absorbs almost all light wavelengths that hit it and reflects very little back. This absorbed energy is converted into heat.

  • All colors of light travel at the same speed in a vacuum.

    • The different colors have different frequencies and wavelengths.

    • If a color has a high frequency (like blue), it has a short wavelength.

    • If a color has a low frequency (like red), it has a long wavelength.

    • This balance allows them all to maintain the same speed.