Why is there a shadow 20, why is there a shadow

An optical phenomenon where the shadow is not an entity, but just a projection. Shadows are created by the scientific principle that objects block light.

Light rays travel in a straight line in the same homogeneous medium and cannot pass through the darker areas formed by opaque objects, forming a shadow that we often refer to. (The light here is visible light). Conditions for the creation of shadows:

Shadow formation requires two necessary conditions: light and opaque objects. There are two types of shadows: umbra and penumbra: if you look closely at the shadow under the electric light, you will also notice that the shadow is particularly dark in the middle and slightly lighter around the periphery.

The particularly dark part in the middle of the shadow is called the umbra, and the dark part around it is called the penumbra. The occurrence of these phenomena is closely related to the linear propagation of light. If you place a cylindrical tea tube on the table and light a candle next to it, the tea tube will cast a clear shadow.

If two candles are lit next to the tea tube, two shadows will be formed that overlap but do not coincide. The part where the two shadows overlap is completely black, and this is the umbra; The place where there is only one candle next to the umbra is the half-light and half-dark penumbra. If you light three or even four candles, the umbra will gradually shrink and the penumbra will appear in many layers.

The same is true for objects that can produce shadows composed of umbra and penumbra under electric light. The lamp is made up of a curved filament that emits light, not just one point. Light from one point obscures the object, and light from other points is not necessarily blocked.

Obviously, the larger the area of the luminous object, the smaller the umbra. If we light a circle of candles around the above-mentioned tea tube, the umbra disappears completely, and the penumbra is too faint to be seen. According to the above principle, scientists have made a shadowless lamp for surgery.

It arranges the lamps with great luminous intensity into a circle on the lamp panel to form a large area of light source. In this way, the light can be irradiated to the operating table from different angles, which not only ensures that the surgical field of vision has sufficient brightness, but also does not produce obvious umbra, so it is named shadowless lamp.

Because the object blocks the light, the place that is blocked by the object is not illuminated by the light, and it is black, that is, the shadow.

Light travels in a straight line, and when it encounters an opaque object during propagation, a shadow is formed.

The light is blocked by an opaque object.

Light always travels in a straight direction, and if it is blocked by some opaque object, it cannot penetrate it and move forward, and a shadow will form behind the object.

When the light hits the projection surface (i.e., the place where the projection is observed), the subject that forms the projection (such as your body) blocks the illuminated light, causing the brightness of the part of the projection surface that is blocked by the light to be lower than the brightness of the other parts, and this low brightness part is commonly referred to as the shadow.

Usually people see a shadow that is very dark, so it feels like it's dark. Those who have studied visual psychology will know that the visual sense of black and white is relative. Typical examples:

The movie screen is white, but when you play the movie, you will feel black on it, and the environment will not be completely black, which means that the screen is not completely black.

There are definitely colored shadows, and it is not difficult to do, there are many ways.

For example, do this:

On a white wall, shine green light on it to form a green wall, and then shine a brighter white light on your body and cast it on the green wall, then your shadow on the wall is green. Of course, if there is a big difference in the brightness of the green light and the white light, you may feel that the shadow is black and the rest of the light is white, which is a normal visual and psychological reflection of the person.

Shadow is an optical phenomenon; It is mainly due to the fact that the object blocks the propagation of light, and then creates an opaque object, forming an area of obstacle, and the shadow is not an entity, it is just a projection, mainly using the scientific principle that light is to travel in a straight line.

Shadow is an optical phenomenon in which there is sunlight and there is shadow.

Shadow is an optical phenomenon that is projected by an object that blocks the light. Because there is light in a dim environment, the shadow is not an entity, and the existence of the shadow only means that the object is solid, not transparent.

When encountering obstacles in the process of light propagation, shadows are formed in places where light cannot reach. Shadows are divided into penumbra and umbra.

Where the light can't reach, you can drive the umbra.

Some rays of light are able to reach, and some rays of light cannot reach where a penumbra is formed.

Shadows in reality appear when there is light; The shadow in the virtual is when you are empty in your heart, helpless in life, and worried in your heart.

When light is blocked by an object, a shadow is formed.

Shadows are formed because the object blocks the propagation of light and cannot pass through the darker area formed by the opaque object.

Shadow is an optical phenomenon in which two conditions are necessary for the formation of a shadow: light and an opaque object.

There are two types of shadows: umbra and penumbra

1. The umbra refers to the area where the light emitted by the luminous object (non-point light source) is blocked by a non-transparent object, and the light projected on the screen (or other objects) is completely dark. Here, the light of the luminous body is completely blocked by the object, and no light arrives.

2. Penumbra refers to the shadow area around the celestial umbra where some light passes through. It is conical in shape, with the tip pointing towards the sun. Its boundaries are intangent to the Moon (or Earth) and the Sun.

Only part of the sun can be seen in the penumbra. When the moon's penumbra sweeps over the Earth, a partial solar eclipse occurs. In terms of imagery, the penumbra is the main obstacle to understanding objects by looking at images, and the penumbra is also known as blurred shadows.

Due to the scientific principle that objects block light. Light rays propagate in the same homogeneous medium along straight lines and cannot pass through the darker areas formed by opaque objects, and the resulting projection is a shadow. Shadow is an optical phenomenon that is necessary for the formation of two necessary conditions: light and opaque objects, and shadows are divided into umbra and penumbra.

Because the object blocks the light, this is the principle of grasping fiber. Light rays travel in a straight line in the same homogeneous medium and cannot pass through the darker areas formed by non-circular transparent objects, and the resulting projection is a shadow. Shadow is an optical phenomenon that is necessary for the formation of two necessary conditions: light and opaque objects, and shadows are divided into umbra and penumbra.

Shadow is a dark shadow created by light being obscured or reflected by an object, and is the result of the interaction between light and an object. Light is made up of electromagnetic waves, and when light encounters an object, it produces changes such as reflection, refraction, and absorption.

There are several reasons for the formation of shadows:

1. Light source: The light source is the source of shadows, when the light source emits light and hits the opaque object, the opaque object will block part of the light and form a projection.

2. Reflection of the atmosphere: When the light hits the atmosphere, the reflection of the atmosphere will occur, and it will be projected on the opaque object, forming a shadow loss.

3. Reflection of the ground: When the light hits the ground, the ground will reflect a part of the light to the opaque object, forming a shadow.

In general, light is produced by luminous objects, and when light hits an opaque object, the opaque object will block part of the light and form a projection, which is the ** of shadows.

When light hits an object, if the object is transparent, most of the light penetrates the object and remains in a straight line, leaving a shadow that resembles the shape of the object. If the object is opaque, most of the light will be reflected or scattered by the surface of the object, and only a small amount of light will penetrate the object. This obscured light creates shadows that allow us to see the contours and shapes of objects.

The size and shape of a shadow is influenced by many factors, the most important of which are the size and position of the light source, as well as the shape and size of the occluding object. For example, in daylight, a person's shadow is usually clearer and darker, while in dim light, the edges of the shadow may be more blurred and diffused.

In conclusion, shadows are the result of the interaction between light and objects.

If light travels in a straight line and is blocked by an opaque object, it will form a shadow on the back of the object. Light can pass completely through transparent objects, so completely transparent objects cannot form shadows.

When light passes through a translucent object, it reveals a portion of the light, creating a translucent shadow. Depending on the angle of light, the shape and size of the shadow will be different. The size of the shadow varies depending on the distance of the object from the light source.

The factors that affect the size of the umbra and penumbra area are: the area of the luminous body and the area of the luminous body from the luminous body to the object. The larger the area of the luminaire, the smaller the umbra area and the larger the penumbra area.

The closer the luminous body is to the object, the larger the umbra area and the penumbra area becomes, and the farther away they are, the smaller the area of the two.