Hey janhvi... Here's your answer... Light travels in the straight line because it does not generally interact with the medium and wherever it interacts it does change its path like when it is entering a different medium with different permeability and permittivity(denser or rarer). This interaction and bending of light is called refraction. that's it.. hope it helps.!

Why does light travel in a straight line?

Light travels in a straight line due to the principles of geometric optics and the behavior of electromagnetic waves. This phenomenon can be explained through the concepts of reflection, refraction, and the wave nature of light.

Wave nature of light

Light is an electromagnetic wave composed of oscillating electric and magnetic fields. These fields propagate perpendicular to each other and perpendicular to the direction of light propagation. The wave nature of light allows it to travel in a straight line until it encounters an obstacle or a medium that affects its path.

Reflection

Reflection occurs when light strikes a surface and bounces back. The angle at which light strikes the surface, known as the angle of incidence, is equal to the angle at which it reflects, known as the angle of reflection. This principle is described by the law of reflection. When light reflects off a smooth surface, such as a mirror, it follows a straight path as the angles of incidence and reflection are equal.

Refraction

Refraction occurs when light passes from one medium to another, causing a change in its speed and direction. It happens because light waves travel at different speeds in different materials. When light travels from a less dense medium to a denser medium, like from air to water, it bends towards the normal (an imaginary line perpendicular to the surface). Conversely, when light travels from a denser medium to a less dense medium, like from water to air, it bends away from the normal. This bending of light is described by Snell's law. Refraction can cause light to change direction but still travel in a straight line within each medium.

Interactions with obstacles

When light encounters an obstacle, it may scatter or be absorbed depending on the nature of the obstacle and the wavelength of light. However, in the absence of any obstacle, light will continue to propagate in a straight line.

Conclusion

In conclusion, light travels in a straight line due to the wave nature of light, the principles of reflection and refraction, and the absence of obstacles. These phenomena explain why light can propagate through space and various media without deviating from its original path, allowing us to observe and interact with the world around us.