A light wave is traveling through the air and then enter water. How will the light change?
It will change color.
It will become brighter.
It will move at a different speed.
It will stop completely.
Light and sound waves can both move through matter, but only light waves can travel through- *
air
water
darkness
a vacuum
The Correct Answer and Explanation is:
1. How will light change when it enters water?
The correct answer is: It will move at a different speed.
When light moves from one medium to another, such as from air into water, its speed changes due to the difference in the optical densities of the two media. This change in speed causes the light to bend, a phenomenon known as refraction. The speed of light is faster in air (approximately 3.0 × 10^8 m/s) than in water (approximately 2.25 × 10^8 m/s). The change in speed is responsible for the bending of light as it enters the water at an angle.
Why does the light not change color, become brighter, or stop completely?
- Color Change: While the speed of light changes as it enters water, the wavelength of the light also changes (because the speed changes while the frequency remains constant). However, this does not cause a change in the color of the light for most cases, especially if the light is white. The change in wavelength is typically too small to significantly shift the light into another color.
- Brightness: The brightness of light is primarily affected by how much light is absorbed or scattered in the medium, not by refraction alone. As light enters water, its intensity might decrease slightly due to absorption, but it doesn’t generally become brighter.
- Stopping Completely: Light cannot stop completely when passing from air to water unless the conditions are extreme (such as complete absorption, which typically happens with opaque objects). Under normal circumstances, light continues to propagate, though it may be slowed down.
2. Light and sound waves can both move through matter, but only light waves can travel through –
The correct answer is: a vacuum.
Light waves, which are electromagnetic waves, do not require a medium to travel through. This is why light can travel through a vacuum, such as space. In contrast, sound waves are mechanical waves and require a medium (such as air, water, or solid materials) to propagate. In a vacuum, there are no particles to carry the sound, so it cannot travel through it. This is why there is no sound in space—there’s no medium for the sound waves to move through.
Explanation:
Light and sound are both waves, but they behave differently due to their nature. Light waves are part of the electromagnetic spectrum, which includes other types of waves like radio waves, microwaves, and X-rays. These waves do not require a medium to travel through, meaning they can propagate through empty space (a vacuum).
Sound, on the other hand, is a mechanical wave, which means it needs a medium (solid, liquid, or gas) to carry the vibration of the wave. Without a medium, sound waves cannot exist, which is why space, being a vacuum, is silent.