## Chapter 45: Electromagnetic Induction
All eyes were fixed on the podium, eager to see what kind of achievement could have made the usually composed and calm Mr. Michael Faraday so excited.
Faraday smiled and said, “I believe many of you in the audience are aware that the world has been researching electricity and magnetism for many years.
However, in the early days, scientists believed these were two separate and independent disciplines.
But the merchants disagreed with us.
Because in the 18th century, a London merchant made an astonishing discovery: a box of iron spoons, after being struck by lightning, surprisingly became magnetic.
This divergence of opinion between scientists and merchants wasn’t resolved until 1820, when Danish scientist Hans Oersted conducted an experiment.
He placed an electric wire parallel to a magnetic needle. When he turned on the electric current, he was surprised to find that the needle twitched.
After repeated experiments, Oersted confirmed this wasn’t a coincidence. He soon published a paper titled “Experiments on the Effect of the Electric Current on the Magnetic Needle.” The scientific community hailed this great discovery as the “magnetic effect of electric current.”
From then on, we humble scientists finally realized that electricity could generate magnetism.
When I entered the field of electrical research under the guidance of my mentor, Humphry Davy, my first thought was: if electricity can generate magnetism, can magnetism generate electricity?
For this hypothesis, I’ve conducted countless experiments over the years. Finally, not long ago, I received a startling answer.
Electricity can generate magnetism, and magnetism can indeed generate electricity. Electricity and magnetism are not independent disciplines, but unified subjects with a strong correlation!”
With that, Faraday lifted the black cloth covering the experimental table.
Before everyone was a six-inch iron ring tightly wrapped with white cloth, with two strands of insulated copper wire wrapped around the left and right halves of the ring.
The left copper wire was connected to a set of handmade batteries, forming an independent circuit.
The right copper wire was only connected to an ammeter.
Faraday enthusiastically introduced everyone: “As you can see, these two circuits are independent and unconnected. We call the circuit with the battery on the left A, and the one on the right without the battery but connected to the ammeter B.
Therefore, according to our common sense, even if we turn on circuit A, the ammeter needle in circuit B shouldn’t move.
But is that really the case?”
Faraday smiled and walked forward. He gently flipped the switch on circuit A.
Under everyone’s watchful eyes, everyone present noticed that the ammeter needle in circuit B deflected slightly in a clockwise direction, but quickly returned to its original position.
When Faraday turned off the switch, the ammeter needle deflected counterclockwise.
“My goodness!”
“What’s going on?”
Someone exclaimed: “Mr. Faraday, isn’t this because you shook the table?”
Faraday jokingly replied: “Although the Royal Society has always been short of funds, we’re not so poor that we can’t afford a suitable experimental table. If you don’t believe me, you can try it yourself. From now on, my hands will be off the table.”
He invited the gentleman who had questioned him to the stage. The gentleman tried seven or eight times, carefully examining the experimental table, before exclaiming:
“Although I know your lectures are always very exciting, this is undoubtedly the best one ever! Please allow me to represent the audience and express our utmost respect to you.”
With that, the gentleman took off his hat, pressed one hand to his chest, and bowed slightly.
The audience erupted in thunderous applause once again.
Just then, another gentleman stood up from the lecture hall.
He questioned: “Mr. Faraday, although I don’t mean to offend, I wonder if there might be a short circuit in the iron ring you used?
After all, both circuits are connected to the iron ring. Although you insulated it with white cloth, there might still be current flowing through the ring.”
Hearing this question, Faraday didn’t answer directly but smiled and said, “If that’s the case, then please watch the second experiment.”
With that, he lifted the black cloth covering another experimental table.
This time, the experimental setup was much simpler: just an ammeter, a hollow coil wrapped with copper wire, and two copper wires connecting them.
Faraday took a magnet from his pocket and placed it into the hollow coil.
The magnet flashed past, through the coil and landed on the table. At the same time, the ammeter deflected.
Faraday smiled and said, “Sir, you see. This time, I didn’t even use a battery.”
The audience exclaimed in unison: “God! This might be the biggest discovery of the year!”
“Mr. Faraday, by unifying electricity and magnetism, you might achieve this feat on par with Sir Isaac Newton.”
To the audience’s applause, Faraday simply nodded in response, a radiant smile on his face. Though he was happy to see his academic achievements recognized, he didn’t forget his mission.
Conducting experiments was just the first step. The most important thing was to gain experience through experiments, summarize them into a verifiable conclusion, and explain the reasons and analysis process behind this phenomenon.
Eldred in the audience saw Faraday’s magic-like experiments and heard him start talking about magnetic lines of force and other terms, only to find himself feeling dizzy and confused, unable to understand anything.
He nudged Arthur next to him with his elbow and whispered, “Do you understand?”
Arthur raised his eyebrows and winked at him: “I understand a little. To be honest, this is the second time I’ve heard it.”
“Ah? Did you secretly come to the lecture before? Why didn’t you tell me?
Forget it, forget it. Tell me, what’s the deal with those messy magnetic lines of force, and how do you distinguish the direction of current and magnetic field?
This stuff is too difficult. I finally came to listen to a lecture, I have to learn something. Otherwise, I won’t know what to say when I chat with those beautiful ladies who like science.”
Arthur said: “I’ll teach you an easy way to remember.”
Eldred curiously asked: “What easy method?”
Arthur said: “If you want to distinguish the direction of the current, then extend your right hand. Keep your four fingers together, and your thumb perpendicular to the other four fingers.
Yes, that’s right, keep all five fingers on the same plane.
Next, point your palm towards the N pole of the magnetic field and your thumb towards the direction of conductor movement, which is the direction of the magnet falling.
Then, the direction your remaining four fingers point is the direction of the induced current.”
Eldred was amazed: “Arthur! You’re a genius! How did you come up with this?”
Arthur avoided answering this: “Do you want to learn how to determine the direction of the force on the conductor?”
“Yes, of course I want to learn!”
“Then shut up and hold out your left hand.”
“Oh? You’re using your left hand this time?”
“Don’t talk so much, just listen to me…”
Before Arthur could finish his sentence, a gentle voice suddenly sounded in his ear.
“Excuse me, what are you talking about?”
Arthur turned his head and saw Faraday standing next to him and Eldred, somehow. The two ordinary boys instantly became the focus of everyone’s attention.
Faraday smiled kindly: “Officer, can you explain the right hand again? I only heard half of it. As for the left hand, we can talk about it later.”
(End of Chapter)
I remember reading about this principle in school but now I don’t remember anything. Do you guys remember reading about this?
Another thing, I though Eldred was a mistranslation, but it seems it exists. This is what I found in google. “English: variant of Aldred. This form of the surname is widespread in eastern England, especially in Essex.”