What is the physics of the phenomenon of light?

Light phenomenon 1, light propagates in a straight line in the same homogeneous medium. The linear propagation of light can explain many common phenomena, such as shadow formation, solar and lunar eclipses, etc. 2. Light is a straight line that indicates the direction of propagation of light.

When drawing light, it is necessary to use arrows to indicate the direction in which the light travels. 3. The speed at which light travels in different media is not equal. The velocity of light in a vacuum is the maximum, which is 3 108 m s.

The velocity of light in other media is less than the velocity in a vacuum. The velocity of light in air is close to the velocity of light in vacuum and can also be considered as 3 108m s. 4. When the light hits the surface of the object, the light will be reflected by the surface of the object, which is called the reflection of light.

5. The line ON perpendicular to the mirror surface made from the incident point of light o is called the normal. The angle between the incident ray and the normal is called the angle of incidence and is denoted by the symbol i. The angle between the reflected ray and the normal is called the reflection angle, which is represented by the symbol r.

6. The law of reflection of light: a. The reflected ray, the incident ray, and the normal are on the same plane. b. The reflected rays and the incident rays are separated on both sides of the normal.

c. The angle of emission is equal to the angle of incidence. 7. The smooth surface reflects the light in the same direction, which is called specular reflection. 8. The uneven surface will reflect the light in all directions, which is called diffuse reflection.

9. Whether it is specular reflection or diffuse reflection, the reflection of each ray of light obeys the law of reflection of light. 10. The characteristics of plane mirror imaging: the distance between the image and the object and the mirror surface is equal; The image is the same size as the object; The connection line between the image and the corresponding point on the object is perpendicular to the mirror surface (that is, the image and the object are symmetrical with respect to the mirror surface); The image of a flat mirror is a virtual image.

11. Virtual image: It is not formed by the intersection of actual light and cannot be undertaken by the screen. 12. When light is obliquely emitted from one medium to another, the direction of propagation will generally change, and this phenomenon is called the refraction of light.

Even if it is the same medium, light can be refracted if the medium is not uniform. The direction of propagation does not change when light is directed perpendicular to the interface. 13. The angle between the refracted ray and the normal is called the refraction angle.

14. When the light is obliquely reflected from the air into the water or other medium, the refracted ray is deflected in the normal direction, and the angle of incidence is greater than the angle of refraction; When light is obliquely emitted into air from water or other medium, the refracted rays are deflected in the direction of the interface, and the angle of refraction is greater than the angle of incidence. (The angle between the light and the normal in the air is always relatively large, that is, the "empty angle is large") 15. The depth of water seen by the eye is shallower than the actual one; Chopsticks inserted diagonally in the water appear to bend upwards in the water; Seeing the sun set below the horizon; When spearing a fish, aim for the underside of the fish; Phenomena such as mirages are caused by the refraction of light. 16. The concave mirror (reflection) can make the parallel light converge, and it can be used to make a solar cooker.

According to the reversibility of the optical path, placing the light source on the focal point can reflect the principle of a parallel light - a flashlight. 17. The convex mirror (reflection) can diverge the parallel light, and it can be used to increase the field of view. Examples:

Rearview mirrors in cars, mirrors on street corners. 18. In the reflection and refraction of light, the optical path is reversible.

The basic principles of geometric optics are three: the linear propagation of light, the reflection of light, and the refraction of light. The rest is just some math problems. The more advanced is the classical theory of the electromagnetic theory of light, which is summarized as Maxwell's equations; At a higher level, quantum mechanics is an all-encompassing field, and there is no single explanation for optics that all physicists can agree with.

In physics textbooks, in the teacher's mouth, in classmates' notebooks, everywhere.

Reflection, refraction, diffuseness, dispersion.

Refraction of light: After the light passes through the magnifying glass, there are virtual images and real images, and the real images are inverted, reduced or equal in size, which can be undertaken by the light screen. The virtual image is upright and enlarged, and cannot be undertaken with a light screen.

Reflection of light: Flat mirror imaging, the image is as large as the real thing.

Diffuse reflection: A beam of light passes through uneven ground, as if reflected in all directions, so it can be seen from all angles.

Dispersion: A beam of light is refracted into seven colors through a prism, called a spectrum, which are: red, orange, yellow, green, indigo, violet. Red light is called infrared, and ultraviolet light is called ultraviolet. These two types of light are mostly invisible to the naked eye.

Light is a physical term whose essence is a stream of photons in a specific frequency band. A light source emits light because the electrons in the light source gain extra energy. If the energy is not enough to make it jump to a more outer orbit, the electrons undergo an accelerated motion and release the energy in the form of a wave.

If the transition is followed by just filling the vacancy in the orbital and going from the excited state to the stable state, the electron will not move. Otherwise, the electrons jump back to their previous orbits again and release energy in the form of waves.

There are three laws of light propagation:

1) The law of linear propagation of light is as described above. Geodetic surveys are also based on this.

2) The law of independent propagation of light. When two beams of light meet each other in the process of propagation, they do not interfere with each other, and continue to propagate in their respective ways, and when the two beams of light converge at the same point, the light energy at that point is simply added.

3) The law of reflection and refraction of light. When light travels through the interface of two different media, part of it is reflected and part of it is refracted. Reflected rays follow the law of reflection, and refracted rays follow the law of refraction.

The color of the object you see is the color of the light that enters your eyes, and the red light is reflected back to the red light no matter what color it hits the object, and the red light that enters your eyes is of course the red light.

Yellow objects only reflect red and green light, and at the moment only red light is reflected.

When you are in front of a street lamp: the lamp shines on the water surface, and the mirror reflection light directly enters your eyes, and the bright light is the water surface, and the diffuse reflection light occurs in other places to enter your eyes, and the light is darker.

When the street lamp is behind you: the lamp shines on the surface of the water, and the mirror reflection light hits the place where it objectively exists, and it does not enter your eyes, the water surface you see is dark, and the diffuse reflection light from other places enters your eyes, of course, brighter than the water surface, look at the picture I drew.

Although we are exposed to and applied to light every day, we have to ask: what is light? But few people can give a precise definition.

In classical physics, particle theory holds that light is made up of individual photons. By the late seventeenth century, Christian Huygens had developed the wave theory, arguing that light was a special wave rather than a collection of particles. In 1807, Thomas Young further confirmed this theory with the diffraction behavior of light.

However, at the same time that people decided to accept the new wave theory, they did not know how to explain the specular reflection behavior of light, which is well understood by particle theory. What exactly is light, a particle, or a wave?

In 1905, Einstein proposed the famous photoelectric effect, believing that when ultraviolet rays irradiate the surface of an object, they will transfer energy to the surface electrons, so that they can get rid of the bondage of the atomic nucleus and release them from the surface, so Einstein interpreted light as a collection of energy - photons. Later generations further deepened this theory and created quantum physics, which believed that all matter has wave-particle duality, but the proportion of the two is different, so light is not only a wave, but also composed of photons. However, light is a unique substance, and its volatility still dominates.

To better understand the volatility of light, let's first take a look at the familiar water waves. Although it is called a water wave, it is not made of water, but is formed by the energy that passes through the water, that is, when you slide your hand in the water, it forms a water wave that propagates from left to right, but this is not the result of the water on the left moving to the right, but you transfer your own energy to the water, which travels in the water in the form of waves, and the water molecules just vibrate up and down and do not leave their original positions. By analogy, all waves are moving energy, and most of them propagate with the help of different mediums similar to water.

The same is true for light waves, only slightly more complex, where energy exists in the form of an electromagnetic field that can propagate in a vacuum without relying on a medium.