# A simple question on the property of light

• Rose Garden

#### Rose Garden

A light source emits light in all directions, and the light travels at light speed, yet when we shut off this light source, all the light rays immediately disappear. I just thought about this and it just seems so strange. When we think of a sound source, we can shut off the sound source but the sound already emitted would keep traveling and echoing. But what about light, when the light source is turned off, what happens to the photons, how can the light already emitted just disappear?

One difference between light and sound is the speed. Sound in air travels about 1000 ft./sec., while light goes around 186000 miles/sec. You can hear the sound echoes because of the time it takes to die off, while for light the die off is essentially instantaneous.

ok there's just so much I don't know: what makes light give off light?

wow That question is more than just a simple question! Nice!

## 1. How does light travel?

Light travels in a straight line at a constant speed of approximately 299,792,458 meters per second in a vacuum. It can also be refracted, or bent, when passing through different mediums such as air, water, or glass.

## 2. What is the electromagnetic spectrum?

The electromagnetic spectrum is the range of all possible wavelengths of electromagnetic radiation, including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. Visible light is only a small portion of this spectrum.

## 3. How does light interact with matter?

Light can be absorbed, reflected, or transmitted by matter. The color of an object is determined by the wavelengths of light that are reflected by its surface. Transparent materials allow light to pass through, while opaque materials block it.

## 4. What is the speed of light in different mediums?

The speed of light varies depending on the medium it is traveling through. In air, light travels at approximately 299,705,969 meters per second. In water, it travels at about 225,000,000 meters per second, and in glass, it travels at around 200,000,000 meters per second.

## 5. How does light behave as both a wave and a particle?

Light exhibits properties of both a wave and a particle. As a wave, it can diffract, refract, and interfere with itself. As a particle, it has energy and momentum, and can exhibit the photoelectric effect. This is known as wave-particle duality, and is a fundamental concept in quantum mechanics.