Chapter 46: Electromagnetic Induction
Chapter 46 Electromagnetic Induction
Everyone’s eyes converged on the lectern, and all the guys wanted to see what kind of result could actually make the always calm and collected Mr. Michael Faraday so happy.
Faraday smiled and said, “I believe that many listeners here know that the world’s research on electricity and magnetism has actually been going on for many years.
But in the earliest days, scientific researchers thought of them as two separate and apart disciplines.
But businessmen disagreed with us.
For in the 18th century, a London merchant made the startling discovery that his box of iron spoons had amazingly become magnetic after a lightning strike.
This disagreement between scientific researchers and merchants wasn’t resolved until 1820, the year the Danish scientist Hans Oster did an experiment.
He placed wires parallel to a magnetic needle, and the moment he passed an electric current, he was pleasantly surprised to find that the needle actually jumped.
After repeating the experiment several times, Oster confirmed that it was not a coincidence. Soon after, he published a paper titled ‘On the Current Impact Experiment on Magnetic Needles’, and the scientific community dubbed this great discovery ‘The Magnetic Effect of Electric Currents’.
From this point on us shallow scientific researchers finally realized that electricity can produce magnetism.
And when I was ordered by my mentor Humphry Davy to move into the field of electrical research, my first thought was – if electricity can produce magnetism, can magnetism produce electricity?
I have conducted countless experiments over the years for this conjecture, and finally, just recently, I got an amazing answer.
Electricity can produce magnetism, and magnetism can indeed produce electricity; electricity and magnetism are not separate and independent disciplines, but a unified discipline with strong correlation!”
At the end of the sentence, Faraday uncovered the black cloth on the experimental table.
Showed in front of everyone is a white cloth densely wrapped six-inch round iron ring, the left and right halves of the ring were wrapped with two strands of insulated copper wire.
The left half of the wires was connected to a set of handmade batteries, forming a separate circuit.
The right half of the copper wire was connected to an ammeter only.
Faraday enthusiastically explained, “As you can see, these two sets of circuits are independent and not connected. The circuit with the battery on the left is called A, and the one on the right, without the battery but with the ammeter connected, is called B.
Therefore, according to our common sense, the ammeter needle of circuit B will not deflect even if we energize circuit A.
But is this really the case?”
Faraday smiled and stepped forward as he flicked on the switch for circuit A.
Under the watchful eyes of the crowd, everyone present noticed that the ammeter of Circuit B actually deflected a little in a clockwise direction, but quickly righted itself back to its original position.
And when Faraday closed the switch, the ammeter actually deflected again in a counterclockwise direction.
“My God!”
“What’s going on here?”
Someone exclaimed, “Mr. Faraday, is this really not because you shook the table?”
Faraday spoke wryly, “Although the Royal Society has always lacked funds, we are not so poor that we cannot afford a proper experimental table. If you don’t believe me, you can come and try it yourself with your own hands. From now on, my hands leave the tabletop.”
He invited the gentleman who had questioned the party onto the stage, and that gentleman tried seven or eight times and carefully examined the table for the experiment before marveling.
“While I know that every one of your lectures has been wonderful, this one is undoubtedly one of the best ever given! Allow me, on behalf of the audience present, to honor you once again.”
At the end of his speech, that gentleman took off his hat and bowed slightly with one hand pressed to his chest.
Once again, the stage erupted in unending applause as well.
Just then, another man stood up at the lecture table.
He questioned, “Mr. Faraday, though I mean no offense. But I think it could be that the iron ring you used for the experiment is leaking electricity?
After all, both circuits were connected to the iron ring, and although you insulated it with a white cloth, perhaps there was still current running down the ring.”
When Faraday heard this query, he didn’t answer positively, but smiled and said, “In that case, please look at the second experiment again.”
At that, he uncovered the black cloth on the table of another experiment. This time the experimental setup was much simpler, with only an ammeter, a hollow coil wrapped in copper wire, and two sections of copper wire connecting the two of them.
Faraday fished a magnet out of his pants pocket and placed it toward the hollow coil.
The magnet flashed through the coil and landed on the table, while the ammeter was similarly deflected.
Faraday smiled and spoke, “You see, sir. This time, I didn’t even use the batteries.”
The audience in the room all exclaimed, “My God! This could be the biggest discovery of the year!”
“Mr. Faraday, by combining electricity and magnetism into one, you will probably be able to rival Sir Isaac Newton with this achievement.”
In response to the audience’s praise, Faraday only slightly nodded his head and returned the salute, his face was filled with a wide smile, although the recognition of his academic achievements made him happy, he still hadn’t forgotten his mission.
Conducting experiments is only the first step, the most important thing is to draw experience through experiments and summarize it into a conclusion that can be repeatedly verified, and explain the causes of this phenomenon and the analysis process.
Elder saw Faraday’s experiments as if by magic, and heard him start to talk about what the magnetic susceptibility and other terms, only to feel dizzy, nothing can be understood.
He used his elbow to pestle Arthur beside him and asked in a low voice, “Do you understand?”
Arthur raised his eyebrows and winked at him, “Slightly. To be honest, this is actually the second time I’ve heard it.”
“Huh? Did you sneak in for a lecture before? How come you didn’t tell me about it?
Forget it, then tell me about that messy magnetic inductance and how to tell the direction of the current from the direction of the magnetic field.
This stuff is too difficult. It’s not easy for me to come to a lecture, so I have to learn a little bit. Otherwise I won’t know what to say when I chat with those pretty ladies who like science in the future.”
Arthur said, “Let me teach you an easy way to memorize it.”
Elder curiously said, “What easy method?”
Arthur spoke, “If you are trying to tell the direction of the current, then hold out your right hand. Keep all four fingers together and keep your thumb perpendicular to the other four fingers.
Yes, that’s it, keep all five fingers in a plane.
Next, align the palm of your hand in the direction of the N pole of the magnetic field, and the thumb in the direction of the conductor’s motion, which is the direction of the magnet’s fall.
Then, the pointing of your remaining four fingers is the direction in which the induced current is generated.”
Elder listened to this and marveled, “Arthur! You are really a genius! How did you come up with this method?”
Arthur avoided answering this, “Do you still want to learn how to determine the direction of a force on a conductor?”
“Learn, of course I want to learn!”
“Then shut up, and then, hold out your left hand.”
“Whoa? Switching to the left hand this time?”
“Don’t bullshit so much, just listen to me ……”
Who knows that before Arthur could finish his sentence, a gentle inquiring voice suddenly rang in his ears.
“Excuse me, what are you talking about?”
Arthur twisted his head to see, Faraday did not know when actually walked to the side of him and Elder, the two boys who were plain and ordinary all of a sudden became the center of attention of the whole scene.
Faraday smiled kindly and said, “Mr. Officer, could you re-tell me the right-handed one? I only heard half of the right-handed one. As for the left-handed one, we can talk about it later.”
(End of chapter)