Light travels as waves. These are transverse waves, like the ripples in a tank of water. The direction of vibration in the waves is at 90° to the direction that the light travels.
Light travels in straight lines, so if you have to represent a ray of light in a drawing, always use a ruler.
Unlike sound waves, light waves can travel through a vacuum (empty space). They do not need a substance to travel through, but they can travel through transparent and translucent substances. The table summarises some similarities and differences between light waves and sound waves:
|Light waves||Sound waves|
|Type of wave||Transverse||Longitudinal|
|Can they travel through matter (solids, liquids and gases)?||Yes (if transparent or translucent)||Yes|
|Can they travel through a vacuum?||Yes||No|
|How are they detected?||Eyes, cameras||Ears, microphones|
|Can they be reflected?||Yes||Yes|
|Can they be refracted?||Yes||Yes|
Light travels extremely quickly. Its maximum speed is approximately 300,000,000 m/s, when it travels through a vacuum.
The very large difference between the speed of light in air (almost 300,000,000 m/s) and the speed of sound in air (343 m/s) explains why you: