shadow of britain

Chapter 46 Electromagnetic Induction
All eyes were on the podium, and everyone wanted to see what kind of results could make Mr. Michael Faraday, who has always been calm and calm, so happy.

Faraday said with a smile: "I believe many listeners here know that, in fact, the world's research on electricity and magnetism has been going on for many years.

But in the earliest days, scientific researchers believed that these were two independent and separate disciplines.

But the merchants disagree with us.

Because in the 18th century, a London businessman astonishingly discovered that a box of iron spoons in him became surprisingly magnetic after being struck by lightning.

This divide between scientific researcher and businessman was not resolved until 1820, when the Danish scientist Hans Oersted performed an experiment.

He placed the wire parallel to a magnetic needle, and the moment he switched on the current, he was pleasantly surprised to find that the magnetic needle actually jumped.

After repeated experiments, Oersted confirmed that this was no coincidence.Soon, he published a paper entitled "On the Current Impact Experiment of the Magnetic Needle", and the scientific community called this great discovery the 'Magnetic Effect of Current'.

Since then, we shallow scientific researchers have finally realized that electricity can produce magnetism.

And when I was transferred to the field of electrical research under the order of my mentor Humphrey David, my first thought was—if electricity can produce magnetism, can magnetism produce electricity?
For this conjecture, I have conducted countless experiments over the years, and finally, not long ago, I finally got an amazing answer.

Electricity can produce magnetism, and magnetism can indeed produce electricity. Electricity and magnetism are not independent and separate subjects, but a unified subject with strong correlation! "

After finishing speaking, Faraday lifted the black cloth covering the experimental table.

In front of everyone's eyes is a six-inch round iron ring densely wrapped with white cloth, and the left and right halves of the ring are respectively wrapped with two strands of insulated copper wire.

The copper wires on the left half are connected to a set of hand-made batteries, forming a set of independent circuits.

The right half of the copper wire is only connected to an ammeter.

Faraday enthusiastically introduced to everyone: "As you can see, these two sets of circuits are independent and not connected. We call the circuit with a battery on the left A, and the circuit on the right without a battery but connected to it. The ammeter is called B.

Therefore, according to our common sense, even if the circuit A is energized, the ammeter pointer of the circuit B will not deflect.

But is this really the case? "

Faraday walked forward with a smile, and he gently turned on the switch of circuit A.

Under the eyes of everyone watching, everyone present found that the ammeter of circuit B deflected a little clockwise, but quickly returned to its original position.

When Faraday turned off the switch, the ammeter actually deflected counterclockwise.

"My goodness!"

"How is this going?"

Someone exclaimed: "Mr. Faraday, isn't it really because you shook the table?"

Faraday said humorously: "Although the Royal Society has always been short of funds, we are not too poor to afford a suitable experimental table. If you don't believe it, you can try it yourself. From now on, my hands Get off the table."

He invited the gentleman who raised the question just now to the stage. The gentleman tried seven or eight times, and carefully checked the experimental table before exclaiming.

"Although I know that every lecture you give is wonderful, this one is undoubtedly the best one ever! On behalf of the audience, please allow me to pay you my respects again."

After saying this, the gentleman took off his hat and bowed slightly with one hand on his chest.

Protracted applause broke out again from the audience.

At this moment, another man stood up on the lecture seat.

He questioned: "Mr. Faraday, although I don't intend to offend. But I think it might be the iron ring you used in the experiment that leaked electricity?

After all, the two circuits are connected to the hoop. Although you have insulated it with white cloth, there may still be current running along the hoop. "

When Faraday heard this question, he did not answer directly, but said with a smile: "In this case, please read the second experiment."

After finishing speaking, he uncovered another black cloth on the experimental table.

This time the experimental setup was much simpler, with only an ammeter, a hollow coil filled with copper wire, and two lengths of copper wire connecting them.

Faraday took out a magnet from his trouser pocket and put it into the hollow coil.

The magnet flashed past, passed through the coil and landed on the table. At the same time, the ammeter also deflected.

Faraday smiled and said: "Sir, you saw it. This time, I don't even use the battery."

The audience present all exclaimed: "God! This may be the biggest discovery of this year!"

"Mr. Faraday, unite electricity and magnetism, and you may perhaps equal Sir Isaac Newton in this achievement."

For the support from the audience, Faraday only nodded slightly in return, with a bright smile on his face. Although he was happy to be recognized for his academic achievements, he still did not forget his mission.

Conducting experiments is only the first step. The most important thing is to obtain experience through experiments, and summarize it into a conclusion that can be verified repeatedly, and explain the reasons and analysis process that cause this phenomenon.

Elder in the audience saw Faraday's magic-like experiments, and heard him talk about terms like magnetic lines of induction. He felt dizzy and couldn't understand anything.

He elbowed Arthur beside him, and asked in a low voice, "Do you understand?"

Arthur raised his eyebrows and winked at him: "I understand a little bit. To be honest, this is actually the second time I've heard it."

"Ah? Did you come to the lecture secretly before? Why didn't you tell me?

Forget it, tell me about the messy magnetic induction lines, and how to distinguish the direction of the current from the direction of the magnetic field.

This thing is too difficult. I finally came to this lecture, so I have to learn a little bit.Otherwise, I don't know what to say when I chat with those beautiful ladies who like science in the future. "

Arthur said, "Let me teach you an easy way to remember."

Elder asked curiously, "What's the easy way?"

Arthur said: "If you want to determine the direction of the current, then stretch out your right hand. The four fingers are close together, and the thumb is perpendicular to the other four fingers.

Yes, that's it, all five fingers are kept on one plane.

Next, align your palm with the direction of the N pole of the magnetic field, and align your thumb with the direction in which the conductor moves, which is the direction in which the magnet falls.

Then, the pointing of your remaining four fingers is the direction in which the induced current is generated. "

After hearing this, Elder said in surprise: "Arthur! You are such a genius! How did you come up with this idea?"

Arthur avoided answering this question: "Do you still want to learn how to judge the direction of force on a conductor?"

"Learn, of course I want to learn!"

"Then shut up, and then, hold out your left hand."

"Oh? This time it's the left hand again?"

"Don't talk so much nonsense, listen to me..."

Unexpectedly, before Arthur finished speaking, a gentle questioning voice suddenly sounded in his ear.

"Excuse me, what are you talking about?"

Arthur turned his head and saw that Faraday had walked beside him and Elder at some point, and the two ordinary boys suddenly became the focus of attention of the audience.

Faraday smiled kindly: "Mr. Police Officer, can you tell me about the right-hand one again? I only heard half of the right-hand one. As for the left-hand one, we can talk about it later."

(End of this chapter)