-
Anonymous users2024-02-06Light propagates in a straight line and is refracted and reflected, and heat is a three-state six-variation.
-
Anonymous users2024-02-05All have the reflection of light, and the fish in the water also have refraction.
The small bright spot has nothing to do with the imaging distance, it is not a finished image, it is just a focus. That's fine, that's how the focus distance is judged.
In the crystal, the straight line segment indicates that the crystal is melting, it is a mixture, and the temperature does not change as you said, and when it reaches point C, it means that it is completely melted, and it is a liquid, so the heating temperature will change. As for the part before point B, it is another form of crystal, and it can be determined that it completely becomes a crystal after heating to six minutes, but it is not known what form it is.
The change of state of matter that is not limited by temperature is the evaporation of the liquid and the sublimation of the solid, and both evaporation and sublimation occur at any temperature.
The last problem feels rather strange, and can only be explained as reaching the boiling point but not continuing to heat, and not meeting the boiling conditions, that is: 1 to reach the boiling point. 2. Continue to absorb heat.
-
Anonymous users2024-02-04Optical direct, reflective, refractive.
1x focal length is not not imaging, which means that the luminaire is not imaged within 1x focal length or 1x focal length, and the sun is about 1500000 kilometers away from your magnifying glass, it is impossible not to image, and the image it becomes is the bright spot.
Change of state of matter. The crystal melting process refers to the BC segment on the way.
The evaporation of the liquid and the sublimation of the solid can occur naturally, and the boiling point of the soup cannot be the same as the boiling point of the water regardless of the temperature, and you should say that the temperature of the soup is the same as the temperature of the water, then the soup in the cup (will not) boil, that is because the boiling point of water containing impurities is higher than that of pure water.
-
Anonymous users2024-02-03The trees on the shore belong to the direct rays of light Fish in the water belong to the refraction of light The birds in the air belong to the direct rays of light The clouds in the water belong to the reflection of light.
The focal length of the convex lens, the meaning of the focal length itself is the distance when the parallel light converges into a point, although the sunlight is not strictly parallel light, but in normal times, it is also regarded as a parallel light, in addition, it is recommended that you check the textbook to see how many times the focal length of the image, how do I remember that it is twice the focal length.
Change of state of matter: The temperature remains constant during the melting of the crystal, although it is constantly absorbing heat. It is important to note that crystals are the most common crystals, and the most common crystal is water. The ab segment in the diagram you provided represents the change of the ice cube when it continues to heat up, and the bc segment represents that the ice begins to melt into water, and the temperature is unchanged at this time, that is, the diagram is parallel to the time axis, perpendicular to the temperature axis, and this temperature value is called the melting point, and the melting point of water is zero degrees Celsius.
The state is an ice-water mixture, more and more water, less and less ice, and at point C, the ice completely turns into water, continues to heat, and the temperature continues to rise.
Crystal melting and boiling is only the same temperature, maintained at the melting point and boiling point, the same taking water as an example, when it is solid, it is ice, the ice reaches zero degrees Celsius, and there is still heat transferred to it before it can melt into water, and at the same time keep the temperature unchanged, and wait until it completely becomes water, and then continue to heat until it is 100 degrees Celsius, there is still heat coming in, so that it can boil, and at the same time maintain the temperature at the boiling point.
In fact, like 2, although the soup in the cup reaches the boiling point of 100 degrees Celsius, there is no way to continue to absorb heat, because the outside water is boiling, the temperature is maintained at 100 degrees Celsius, there is no temperature difference, and there is no heat transfer.
-
Anonymous users2024-02-02Because the light is sent out and reflected back, it is shared, so the time of a one-way trip is divided by 2The speed of light is 3 times 10 to the eighth power, and multiplying the speed by time is the distance from the Moon to the Earth.
There are two kinds of light sources: natural and artificial, light in a homogeneous medium, propagating along a straight line, the role of a plane mirror is to image, and it can also change the direction of light propagation, and the periscope is a plane mirror that uses the property of changing the direction of light propagation.
Calm. All of them have the properties of plane mirrors, and they can all be formed into an upright and equal size virtual image.
-
Anonymous users2024-02-01Seconds multiplied by the speed of light 3*10 8m s, which is 2 times the distance from the moon to the earth, there are two kinds of light sources: artificial light source and natural light source.
Light travels in a straight line in the same homogeneous medium.
The role of a flat mirror is to change the direction of light propagation.
The periscope is the use of a plane mirror to change the propagation direction of light, all of which have the properties of a plane mirror, and can become an upright virtual image of equal size, and the distance between the object and the image to the plane mirror is equal.
-
Anonymous users2024-01-31The distance is s=1 2vt=3*10 8m s*
Because it is a round trip, it is multiplied by 1 2
Natural light source Artificial light source The same homogeneous medium.
-
Anonymous users2024-01-30There are two kinds of light sources: light source- and anti-light source; Light travels in a straight line in the same group of species.
The role of a plane mirror is; It can be imaged, and it can also be changed in the direction of light propagation. A periscope is a property that uses a flat mirror to change the direction of light propagation; The calm water surface and the polished metal surface all have the property of reflectiveness, and can be formed into an upright and equal size of the virtual image.
-
Anonymous users2024-01-29Natural light source Artificial light source The same homogeneous medium.
Imaging Change Change the direction of light propagation Flat mirror imaging Upright virtual image.
-
Anonymous users2024-01-282.Natural light source Artificial light source.
3.Imaging changes reflection imaging orthodoxy.
-
Anonymous users2024-01-27The distance is s=vt=3*10 8m s*
Because it is a round trip, it is multiplied by 1 2
-
Anonymous users2024-01-26Natural light source, artificial light source, vacuum, dress, change, reflection, reflection, equidistant from the reflective surface, virtual image.
-
Anonymous users2024-01-25The laser is shot from the ground to the moon and reflected back to the earth by the surface of the moon, and the distance from the moon to the earth is 375000000 meters.
There are two types of light sources: natural and artificial; Light travels in a straight line in a uniform ring.
The role of a plane mirror is; It can be imaged, and it can also be changed in the direction of light propagation. A periscope is an image-making property that uses a plane mirror; The calm water surface and the polished metal surface all have the property of being imaged, and they can all be formed into upright and equal-sized virtual images.
-
Anonymous users2024-01-24Of course, light has a frequency. Light is an electromagnetic wave (visible spectrum) that can be seen by the human eye. In the scientific definition, light sometimes refers to the entire spectrum of electromagnetic waves.
Light is made up of a type of elementary particle called a photon. You may not understand the particle and wave properties, or wave-particle duality, but to put it simply, light can be a particle or an electromagnetic wave, and electromagnetic waves have frequencies like other waves. The frequency of harmony is the same, however, the frequency of light is much faster.
As for the wavelengths of light, there are many, and I have summarized them as follows:
The wavelength of visible light (4*10-7m---7*10-7m) can be seen.
Light color --- wavelength (nm) – represents the wavelength.
Red--780 630 --700Orange--630 600 --620yellow--600 570 --580 Green -570 500 --550 Cyan -500 470 --500Blue -470 420 --470Violet --420 380 -- The main difference between 420 ultraviolet and infrared is that they have different wavelengths, different characteristics, and different uses. Ultraviolet wavelength, it can harm**. Infrared rays mainly have the effect of radiation, which produces high temperatures.
Ultraviolet rays such as the sun will produce ultraviolet rays, which can sterilize and disinfect. Ultraviolet rays are invisible to the naked eye, but infrared rays are different, they have a longer wavelength and can be used as a remote control, and they can be used as sights when shooting at night.
o⊙)…Every day, every day.
Do more exercises. Teach you a quick way to learn, it's as simple as writing the answers on the practice questions and looking at them again, whatever method you use, just memorize them. It's a quick approach, but it's also flawed, and you can find out for yourself!
Of course, you have to listen carefully in class, and the homework left by the teacher must be completed independently, and you should ask questions frequently if you don't know, or wait for the teacher to talk in class (junior high school class time is relatively relaxed, the teacher should teach the exercises, if you don't talk about it, ask the teacher, the teacher will not say you). In addition, don't look for too many and too difficult extracurricular questions, which will increase the pressure, but a moderate amount is still possible. The content of the third year of junior high school here is more than the content of the second year of junior high school, and the part of electricity must be learned well. >>>More
Send me an email and I'll send you seven or eight.
At the beginning of high school, you have to establish a firm belief that you must be admitted to a good university, and then go all out for your ideals, you can learn while playing in junior high school, but you can't in high school, and you will fall behind if you slack off. A very important point in high school learning is self-control, you must control yourself, when to do what you do, you must understand yourself, don't blindly follow the trend, be a rational student, most of the teacher's words are classics, try to keep them in mind, and it will definitely not harm you. The tactics of the sea of questions will never go out of style, understanding and doing are two different things, don't look at the masters, you must do it, which can make perfect, right. >>>More
If the son is a year old 12 years ago, the father is 10 years old. >>>More