What are the basic laws of light propagation? What are the requirements for the light source for lig

The basic laws of light propagation are:

1. In a homogeneous medium, light travels in a straight line. The expansion shows that in any dimensional space, light travels along the shortest path.

2. Light is reflective.

3. Light has a refraction phenomenon.

4. Light interferes.

5. Light has diffraction.

6. The propagation of light also has particle properties, such as the photoelectric effect.

Interference of light. The light source of the experiment requires the light to have the same frequency and the same initial phase (so the light emitted by the same light source should be as parallel as possible).

Experiments generally use point light sources, and the light emitted by point light sources theoretically forms a spherical surface and propagates outward. Because the gap is small, the light passing through a small area can be seen as approximately parallel.

The basic law of light propagation is Fermat's principle, that is, light always propagates along the path of the extreme value of the optical path, and the reaction in the same homogeneous medium is that the light travels in a straight line!

The light interference experiment requires the light source to have good coherence, that is, the frequency of the light that the light source can provide is as single as possible, the vibration direction of the light is as consistent as possible, and the length of space is as small as possible!

When interfering, the diffracted light is generated by the slit, so that the light incident on the slit can be turned into multiple beams of light with the same basic properties as the incident light!

Let's see what others have to say.

The interference and diffraction phenomena of light indicate that light has a wave nature.

1. Light interference phenomenon: two columns of light waves with the same frequency are superimposed when they meet in the air, and they are always strengthened in some areas and weakened in other areas, and the phenomenon of light and dark stripes or colored stripes is called light interference.

2. Diffraction phenomenon: In the process of light propagation, when it encounters obstacles or small holes (narrow slits), it leaves the straight path and goes around the shadow of the obstacle. This phenomenon is called diffraction of light.

The interference and diffraction phenomena of light indicate that light has a wave nature.

Brief introduction. But the weakness of wave theory is that waves, similar to sound waves, require a medium to propagate. Although there was a hypothesis of luminous aether, it was also strongly questioned by the 19th-century experiments of Michael Murray.

Newton speculated that the speed of light became higher at high densities, and Huygens and others felt the opposite. But there were no conditions to accurately measure the speed of light until 1850, when Léon Foucault's experiments yielded the same results as wave theory. And it was at this moment that classical particle theory was truly abandoned.

The interference of light and the conditions that produce it.

Light interference is a phenomenon in which two or more columns of light waves overlap in space to form a new light waveform. Only two columns of light waves with the same frequency, constant phase difference, and the same direction of vibration can produce light interference. It is impossible for the light emitted by two ordinary independent light sources to have the same frequency, let alone a fixed phase difference, so there can be no interference.

In physics, interference refers to the phenomenon in which two or more columns of waves overlap in space, resulting in the superposition of new waveforms.

For example, if a beam splitter is used to divide a monochromatic beam into two beams, and then let them overlap in a certain area of space, it will be found that the light intensity in the overlapping area is not uniformly distributed: its brightness varies with its position in space, the brightest place exceeds the sum of the light intensity of the original two beams, and the darkest place may have zero light intensity, and this redistribution of light intensity is called "interference fringes". Historically, the phenomenon of interference and its related experiments have been an important basis for proving the wave nature of light, but this interference property of light was not gradually discovered until the beginning of the nineteenth century, mainly because of the difficulty of obtaining coherent light sources.

Conditions for the occurrence of interference phenomenon: when two columns of waves propagate in the same medium and overlap, the particles of the medium within the overlap range are affected by two waves at the same time. If the amplitude of the wave is not large, the vibrational displacement of the medium particles in the overlapping range is equal to the vector sum of the displacements caused by the respective fluctuations, which is called the superposition principle of waves.

If the crest (or trough) of two waves arrives at the same place at the same time, the two waves are said to be in phase at that point, and the interference wave will produce the largest amplitude, which is called constructive interference (constructive interference). If the crest of one of the two waves arrives at the same place at the same time as the trough of the other wave, the two waves are said to be inverted at that point, and the interference wave will produce the smallest amplitude, which is called destructive interference (destructive interference).

The conditions for two columns of light to produce interfering light and dark fringes are:

Bright lines: δ=k

Dark lines: δ=2k+1), k=0,1,2......When k is an even number, the optical path difference is an integer multiple of the wavelength, the amplitude increases, the light intensity increases, and the light intensity is bright. K is a dark stripe when it is an odd number. Therefore, it can be seen that the brightness is constant at a certain distance x, and with the change of x, light and dark alternately, that is, interference fringes are generated.

When the interference phenomenon of light occurs Tongpai cracking, it is often accompanied by the generation of light and dark fringes, such as Newton's ring, Young's double slit stem involvement, etc., which will be accompanied by the generation of interference fringes.

Light has two properties: 1 wave and 2 particle.

Interference and diffraction illustrate that light has the properties of waves, and light is an electromagnetic wave.

It has energy in itself.

These two phenomena illustrate the fluctuating nature of light.

And the photoelectric effect.

Illustrates that light is particle-like.

(1) Under normal circumstances, the path of light propagation is invisible, we can use a red laser beam with relatively concentrated energy, or add a few drops of milk to the liquid, and put it in a darkly lit room to observe, so that it is easier to see the path of light propagation

2) To ** whether the reflected light and the incident light are in the same plane, the cardboard 2 can be folded forward (backward) to observe whether there is reflected light on the cardboard 2

3) Choose a glass plate instead of a flat mirror to determine the observation and determine the position of the image, and choose two identical candles to compare the relationship between the size of the object and the image

4) Since the image is formed by the reflection of light, and both sides of ordinary glass can reflect light and can form two images, so through the glass plate, the student saw two images of the same candle

5) The image and the object are about the symmetry of the mirror, the glass plate should be placed vertically during the experiment, if it is not vertical, the image will be high or low, the back candle is placed on the table, no matter how you move the back candle can not completely coincide with the image of the front candle

6) One of the imaging characteristics of the plane mirror: it can be seen that the size of the candle imaged by Xiaohong remains unchanged when the candle is far away from the glass plate or close to the glass plate

7) An experiment is not representative, and the same experimental scheme should be taken to do it several times to avoid the accident of the experimental phenomenon, so as to ensure the correctness of the conclusion, so the B operation should be taken

So the answer is: 1) using a red laser beam;

2) fold the cardboard 2 forward (backward) and observe whether there is a reflected light on the cardboard 2; (3) It is easy to find the position of the image; Size; (4) The glass is thicker, and the two reflective surfaces are reflected twice; (5) The glass plate and the table top are not vertical; (6) unchanged; （7）b．