physics

1) Refraction: When light passes from one medium to another, such as water or air, and changes direction, it demonstrates that light travels in a straight line. 2) Shadow: When an opaque object, such as a person, blocks the direct path of light, it casts a shadow in a straight line. 3) Laser Beam: A laser beam is a high-intensity light that travels in a straight line and can be used in many applications such as cutting and welding. 4) Reflection: When light hits a reflective surface, such as mirror, and bounces off in a straight line, it demonstrates that light travels in a straight line.