Light can travel through some materials, such as glass or water. Light also can travel through empty space, like from the sun to Earth. When light travels from one location to another, it goes in a ______.

Light can travel through some materials, such as glass or water. Light also can travel through empty space, like from the sun to Earth. When light travels from one location to another, it goes in a ______.

• A. Circle
• B. Ellipse
• C. Straight line
• D. Spiral

Answer: (C)

Light travels in a straight line through a uniform medium. When light moves through air, water, glass, or empty space without hitting anything that bends it, its path is a straight line from the source to your eye. The reason it sometimes changes direction is when it encounters a boundary between materials with different optical properties or reflects off a surface; inside each uniform material, though, the path remains straight. The shapes listed would require ongoing bending, which isn’t how light behaves in a consistent medium. So the most direct, unaltered path light takes is a straight line.

Light travels in a straight line through a uniform medium. When light moves through air, water, glass, or empty space without hitting anything that bends it, its path is a straight line from the source to your eye. The reason it sometimes changes direction is when it encounters a boundary between materials with different optical properties or reflects off a surface; inside each uniform material, though, the path remains straight. The shapes listed would require ongoing bending, which isn’t how light behaves in a consistent medium. So the most direct, unaltered path light takes is a straight line.