Chapter 295: Open the door to the microscopic world!
"Gustav, please join us outside."
Hear what Faraday said.
Kirchhoff on the side immediately walked to the other side of the table and took out two electrodes.
Both electrodes are made of metal, but the specific metal type cannot be seen. In short, it is either zinc or aluminum.
Their size is somewhat similar to later tablet computers, about two finger widths thick, and there are some wires connected to the outside.
2k novel
As we all know.
Research on cathode rays is actually a project that spans a long time.
After Plück discovered cathode rays in 1858.
It would not be until early 1879 that Crookes determined its energetic nature.
It would be more than ten years before JJ Thomson revealed its true nature.
But it's different now.
Although Xu Yun did not reveal all the secrets of cathode rays at once, he had already told Faraday many key thinking nodes through his identity as "Fat Fish".
Therefore, Faraday can easily directly omit some meaningless time and maximize the efficiency of the experiment.
For example, from complex property research, jump directly to the current...
Electrical testing.
After taking out the two electrode plates.
Kirchhoff carefully placed the two pieces on both sides of the vacuum tube, fixing them in position to ensure they were parallel to each other.
Then connect the passage to the wires outside the vacuum tube, step back a few steps, and turn on the power.
soon.
With the emergence of electromotive force, an electric field appears between the two charged metal plates.
A few more seconds passed.
The blue-white light in the vacuum tube gradually began to change. From the original straight light, it slowly began to bend.
A little less than half a minute later.
The deflection of the light has been turned to a large degree, which is clearly visible to the naked eye.
See this situation.
The pupils of Faraday, Weber and Gauss shrank at the same time!
Faraday's right hand holding the back of the chair tightened his grip!
be honest.
From the perspective of the phenomenon itself, the deflection of cathode rays is actually very simple:
At this point it is turned towards the metal plate on the left, in the opposite direction of the electric field, and is therefore obviously negatively charged.
But what surprised Faraday and others was not that the phenomenon was so simple on the surface, but because...
Cathode rays actually experience electric field force!
To know.
At the opening ceremony more than a month ago, Xu Yun had already verified the particle theory of light through the photoelectric effect.
At present, this experiment has spread throughout the European scientific research community, helping the particle theory and wave theory return to an equal position.
Under the background of this precondition, cathode rays will also be deflected, which illustrates one thing:
Cathode rays are particle streams of charged particles!
More importantly.
Although visible light has wave-particle duality, its 'particles' are not disturbed by electric and magnetic fields.
Therefore, so far, everyone can only use experiments to prove its physical properties, but it is difficult to 'capture' the existence of such particles.
But light composed of charged particles is different.
It is not as intangible as electric current, because light is a substance that can be observed with the naked eye - this is the wrong knowledge that Xu Yun deliberately guided and formed earlier.
This way.
Coupled with the charged properties of cathode rays, as long as physics and mathematics are combined, some detailed properties of the 'particles' can be studied!
Think of this.
Faraday couldn't help but sigh deeply.
In fact, as early as 12 years ago, when the glow phenomenon was first discovered, he also tried to apply an electric field to light.
However, the vacuum degree of the vacuum tube was low at that time, and the electric field caused ionization of the residual gas.
Ultimately leading to the complete failure of the relevant experiments.
It was the failure of this attempt that made Faraday completely give up the idea of studying the glow phenomenon.
What did I miss in the first place...
Then Faraday took a deep breath, forced the sighs in his heart to be temporarily forgotten, turned to Kirchhoff and said:
"Go on, Gustave."
Kirchhoff nodded, stepped forward and took out a few more pieces of equipment.
One of them is an artificially modified magnetic pole, which is very large but very thin.
The other is an open copper barrel.
The structure of the copper bucket is so simple that it does not even need to be described in words, and its appearance is infinitely close to a smaller version of the iron bucket for soup in later canteens.
But there is another name for this thing, it's called Faraday Cylinder.
When combined with an electroscope, it can verify the power of the battery.
Kirchhoff then placed the entire magnetic pole under the test tube and connected the Faraday cylinder to the anode.
Looking at Kirchhoff who was tinkering with the equipment, Xu Yun suddenly thought of something.
He quietly turned his head and glanced at William Weber beside him without moving his expression.
But as luck would have it.
Weber happened to be looking here at this time, and when he met Xu Yun's gaze, he couldn't help but smile kindly:
"What's wrong, classmate Luo Feng?"
Xu Yun's expression froze when he saw this, and he quickly waved his hands with a dry smile:
"It's okay, it's okay. There seem to be mosquitoes flying in the house. I'll just take a look."
Weber looked around with a confused look.
It’s the end of December, the coldest month, can there still be mosquitoes?
After looking back.
Xu Yun bared his teeth slightly.
Although Mosquito's reason was a bit ridiculous, he couldn't tell Weber that he suddenly thought that Kirchhoff was originally his assistant and now worked for Faraday. He wanted to see if Weber had any Minotaur performance...
.
Ahem...
And while Xu Yun and Weber were talking.
Kirchhoff, who was tinkering with the equipment, also clapped his hands and said to Faraday:
"Professor, the equipment is ready."
Faraday nodded, came to the edge of the table, pointed to the Faraday tube at one end of the anode and said:
"Thank you, Gustave, let's start as planned."
Kirchhoff nodded and quickly came to the Faraday barrel:
"Okay, Professor."
After Kirchhoff is in place.
Faraday first blocked the magnetic pole, and then began to adjust the cathode rays so that they could pass through a slit and enter the Faraday tube inside the anode.
At the same time, he raised his head and asked Kirchhoff:
"Are you ready, Gustave? I'm coming in."
"I'm fine with that, Professor."
"Okay, I'll count down to three, three...two...one...start!"
"...Professor, the feedback is very intense, 20%...43%...59%...83%...It's almost full. It's almost full. Professor, it will overflow if it doesn't stop!"
Click——
Faraday quickly stopped the radiation exposure and gently wiped the sweat from his head.
Fortunately, I stopped quickly, otherwise the electrometer would have exceeded the limit.
That's right, an electrometer.
No one would want to go somewhere else, right?
Then Faraday walked to the electrometer and scanned the value table:
"9.6
Kirchhoff glanced at the stopwatch in his hand:
"15.6 seconds."
Faraday nodded slightly and signaled Gustave to clear the calculation table.
Then another thermocouple was added and the irradiation started for the second time.
The entire process is much the same as the first time, the only variable is that as the light shines in, the thermocouple begins to heat up quickly.
Faraday held the stopwatch and counted the numbers carefully:
"12.5...13.4...15.6 seconds, stop!"
After calling timeout, Faraday looked at Kirchhoff and asked:
"Gustav, how many degrees did the temperature rise?"
Kirchhoff leaned down slightly and carefully compared the scales:
"Hmm...0.338 degrees."
Faraday wrote the number down in his notebook again, and scratched the bottom with the tip of his pen.
Then I thought for a moment and started the last link:
Unlock the magnetic pole that was sealed just now.
All future generations of students who have never scored zero in high school physics should know this.
If a charged particle in a uniform magnetic field only experiences magnetic force, it will make a circular deflection motion.
The person who summarized this phenomenon was called Lorentz, so this force is also called the Lorentz force.
It is worth mentioning that.
The correct pronunciation of this force should be the Lorentz force, which is the person's name plus the force.
Similar ones include Coulomb force, Ampere force, etc.
But perhaps the name Lorenz is too subtle, so teachers and students, including many high school teachers, call it Lorenz Magnetism.
In 1850, Lorentz would not be born for another three years, so naturally he could not come up with the concept of Lorentz force.
But on the other hand.
Lorenz was the generalizer of the phenomenon of charged particles moving in uniform magnetic fields. He first proposed the idea that moving charges produce magnetic fields and that magnetic fields have an effect on moving charges. However, he was not the discoverer of the phenomenon itself.
As early as 1822, the German Owens tried an experiment:
He placed a charged bead into a magnetic field and found that the bead would move in an arc.
The reason why Lorenz can leave his mark in history in related fields is that his contribution is not as simple as proposing a conjecture, but because he summarized a formula such as F=qvB*sin(v,B).
Just like everyone said Mavericks discovered gravity.
This sentence is actually a relatively popular explanation, and it is wrong in a strict sense.
But the public has no need to go deeper, so we have such a relatively broad term.
In the history of science, there are actually not many people who can become gods by relying on pure theory.
So for Faraday and others.
It is not very difficult to balance the magnetic field force and the electric field force by adjusting the strength of the magnetic field.
After applying a magnetic field.
Faraday turned off the metal electrode again and observed the phenomenon.
soon.
Under the action of electromagnetic force, the rays begin to deflect.
Faraday took a magnifying glass and a pre-made scale and recorded the deflection pattern.
What happens next is very simple.
Faraday picked up a pen and paper and wrote a formula on the paper:
Q= Ne.
The origin of this formula is simple.
In the first step, Faraday used an electrometer to measure the amount of electricity Q gained in the metal cylinder over a certain period of time.
If the number of particles entering the cylinder is N and the charge carried by each particle is e, then Q is the product of N and e.
Then Faraday turned another page of the book and wrote another formula:
W= N·1/2mv2.
The meaning of this formula is also very simple:
After the same period of time, the temperature rise is read. If the total kinetic energy W of the particles entering the cylinder is completely converted into heat energy due to collision, then the rising temperature can be used to calculate the total kinetic energy W.
Since the particle is a particle, its kinetic energy must also conform to the kinetic energy formula - let me tell you in advance, the kinetic energy formula was proposed in 1829.
Where m and v are the mass and velocity of the particles respectively, multiplied by the number of particles is the total kinetic energy.
Then we only need to find the radius of curvature R of the particle motion trajectory of the final magnetic pole deflection, and the magnetic field strength H.
Then you can get:
Hev=mv2/R.
Substituting the above three formulas into each other, you can finally get a result:
e/m=(2w)/(H2R2Q) (Thanks, the background is finally optimized now...)
And e/m is...
Charge to mass ratio!
The so-called charge-to-mass ratio refers to the ratio of the charge and mass of a charged body, sometimes also called specific charge.
This is one of the important data of elementary particles and a key step for mankind to open up the microscopic world.
When I first listened to Xu Yun's lecture on the wave equation, in order to make up for Faraday's mathematical proficiency, I gave him a patch of Gaussian soul possession.
But today Gauss has arrived at the scene, so Xu Yun no longer needs to think about asking God.
I saw Gauss taking the pen and paper and quickly starting to calculate on the paper.
five minutes later.
The little old man casually threw away the pen and gently shook the paper in his hand.
I only see this moment.
There is a number clearly written on the paper:
1.6638*10^11C/kg.
Just when Gauss was about to brag a few words, a familiar voice suddenly sounded next to him:
"Ah, it's so strange..."
.......
Note:
I had another acupuncture today, I will update as usual tomorrow, and I will update the day after tomorrow!!!!