What is a ray?
What is a ray? Rays can be seen in many situations, and can be applied to many things. There must be many small Friends want to know more about what rays are. Let’s take a look at what rays are. What is ray 1?
Ray has two meanings: one is a particle or photon beam; the other is a straight line formed by infinite extension of one end of a line segment.
1. A ray (line) refers to a straight line formed by an infinite extension of one end of a line segment. A ray has only one end and its length cannot be measured (it is infinite). Rui is an axisymmetric figure, and its axis of symmetry is a straight line. --This sentence has no theoretical basis, so its correctness cannot be determined.
2. Rays (particles or photon beams) are particles or photon beams with specific energy emitted by various radionuclides, atoms, electrons, neutrons and other particles.
Various rays have different biological effects due to different ionization densities, and the mutation rates they cause are also different. In order to obtain higher beneficial mutations, appropriate rays must be selected, but due to factors such as ray sources, equipment conditions, and safety, gamma rays and x-rays are most commonly used.
Extended information:
Only a few months after Roentgen discovered X-rays, it was used in medical imaging . In February 1896, Scottish doctor John McIntyre established the world's first radiology department at Glasgow Royal Infirmary. X-ray penetration ability is related to its frequency. It has the characteristics of being easily absorbed by high atomic number materials, and a lead plate of about 2-3mm can be used for shielding.
Visible light, infrared rays, ultraviolet rays, etc. are all caused by electrons in the outer layer. Roentgen rays are caused by internal electrons. Gamma rays are caused by atomic nuclei. But it can kill cells, so it can also kill cancer cells for medical purposes. What is ray 2?
1. A straight line is composed of countless points. Straight lines are the components of surfaces and, in turn, of solids. It has no endpoints, extends infinitely to both ends, and its length cannot be measured. A straight line is an axially symmetrical figure.
2. A ray refers to a straight line formed by an infinite extension of one end of a line segment. A ray has one and only one endpoint, and its length cannot be measured (it is infinitely long).
Features:
Only one endpoint and one direction. Immeasurable.
3. A line segment (segment) means that it has endpoints at both ends and cannot be extended, which is different from straight lines and rays.
Properties of line segments:
Among all lines connecting two points, the line segment is the shortest. Referred to as the shortest line segment between two points.
So the sum of two sides of a triangle is greater than the third side.
Extended information
1. Generally speaking, and a common saying in textbooks, a line segment is composed of countless points.
The correct statement is that a line segment is composed of infinite points, and the length of the line segment has nothing to do with the length of the points. Values ??at two different scales cannot be directly extrapolated. Finite and infinite cases cannot be simply extrapolated. Detailed discussion is the stuff of advanced mathematics.
Another way of saying it is to explain it from the perspective of motion: a line segment is the motion trajectory of a point. However, in real life, people have already defaulted to the statement that "a line segment is composed of countless points."
2. Recording and identification of rays
If the endpoint is A and any point on the ray except the endpoint is B, then this ray can be recorded as ray AB.
Note: Endpoint A comes first, and the other point B comes after. Otherwise something will go wrong.
Two rays with the same endpoint and different directions are two different rays.
Two rays with the same endpoints and the same direction are the same ray. What is ray 3?
The difference between straight lines, rays, and line segments
Definition: A straight line has no endpoints, it is straight, and there is no way to measure its length. To determine whether a graphic is a line segment, the above three conditions must be met.
Ray, a ray has only one endpoint, it is straight, and there is no way to measure the length. To judge whether a graphic is a line segment, the above three conditions must be met.
Two rays drawn from a point constitute an angle. This point is called the vertex of the angle, and the two rays are called the sides of the angle.
Different representation methods: Representation method of line segment: First name the two endpoints of the line segment with capital letters. One endpoint is A and the other endpoint is B, then this line segment is AB. There is a knowledge point here, two points determine a line segment.
How to represent a straight line: First name the two points on the straight line with capital letters. One point is A and the other is B. Then this straight line is straight line AB. There is a knowledge point here, two points determine a straight line.
How to represent a ray: A ray can be represented by an endpoint and another point on the ray. The letter of the endpoint (starting point) is written in front and cannot be swapped. If the endpoint of the ray is A and the other point is B, it is ray AB; if the endpoint of the ray is B and the other point is A, it is ray BA.
Uses of straight lines
Can be used as a datum plane. You can also do the center line of the object. You can also make a reference surface. It can be used for whatever you want. It can also be used to create elevations and a series of other things. For example, it can be used as a starting line. It can also be used to create boundary lines, including the national boundaries of each country, as well as transportation. road sign. What's more, they are less used now. I think the ropes used for rice transplanting in the past are made into these rice transplanting ropes and so on.
Application of rays
Infrared rays (wavelengths longer than visible light) have a thermal effect, so microwave ovens use infrared rays. Ultraviolet rays have bactericidal and fluorescent effects, so there are ultraviolet rays for disinfection and ultraviolet rays for anti-counterfeiting. X-rays are used in medical x-rays to check for fractures, etc. Gamma rays have extremely strong penetrating ability, so they can be used for metal flaw detection and medical gamma light knives.
Purpose of line segments
The main purpose of line segments is as a basic element in constructing trend types and serves to build the minimum level center. It does not make much sense in large cycles because line segments It itself has a large future function (line segments must be destroyed by line segments, and a line segment contains at least 3 strokes. If you use a pen-constructed line segment to operate on the daily line, the reaction time will be too long, and you may need to take the elevator several times).
Straight lines
Straight lines are composed of countless points. Straight lines are components of surfaces and then form bodies. They have no endpoints and extend infinitely to both ends. Length cannot be measured, and a straight line is an axially symmetrical figure.
Judgment method
Point and straight line: Generally, the distance between a point and a straight line refers to the shortest distance from the point to the straight line, that is, the vertical distance.
Intersection point of straight lines: Regardless of coincidence, in a two-dimensional plane, two intersecting straight lines can intersect or be parallel.
Angle of intersecting straight lines: If two lines intersect, an included angle will be formed. The included angle between the two lines usually refers to an angle not greater than 90°.
Distance of straight lines: Generally, the distance between two straight lines refers to the shortest distance. In two-dimensional cases, the distance between two intersecting straight lines must be 0.
Ray
A ray refers to a straight line formed by an infinite extension of one end of a line segment. A ray has one and only one endpoint, and its length cannot be measured. We usually see it visually. The light is the light from the flashlight.
Judgment method
If the endpoint is A and any point on the ray except the endpoint is B, then this ray can be recorded as ray AB. Two rays with the same endpoint and different directions are two different rays. Two rays with the same endpoints and the same direction are the same ray.
Line segment
A line segment means that it has endpoints at both ends and cannot be extended. It is different from straight lines and rays. Use a ruler to connect two points to get a line segment. The length of the line segment is the distance between these two points.