I like Analyze the physics of science fiction, so I’m going to argue that Merrie Melodies cartoons”Compressed Hare“Happened in the distant future when animals rule the world. I mean, Bugs Bunny and Wile E. Coyote Walk on two legs, talk, do things. How could this not be science fiction?
Let me set the scene-I don’t think we need to worry about spoiler alerts, because this episode is 60 years old. Of course, the basic idea was that Wile E. Coyote decided that he should eat the rabbit. After several failed attempts to catch the bug, he came up with a new plan. First, he wants to throw a carrot-shaped iron block into Bugs’ rabbit hole.After the carrot is eaten (I don’t know how this will happen), Wile E. Coyote will open one huge The electromagnet pulls the rabbit to his side. This is such a simple and awesome plan, it has to work, right?
But wait! This is the part I really like: When Wile E. Coyote was assembling his device, we saw it in a huge crate labeled “A 10,000,000,000 Volt Electromagnet Do It Yourself Kit”.
In the end, you can probably guess what will happen: Bugs doesn’t actually eat iron carrots, so once the coyote turns on the magnet, it will rush towards him and enter his cave. Of course, there are many other things that will also be attracted to it-including lamp posts, bulldozers, giant cruise ships and rockets.
Okay, let’s break down the physics of this giant electromagnet and see if it will work if Bugs fall in love with it.
What is an electromagnet?
There are basically two ways to generate a constant magnetic field.The first one is to use permanent magnets, like those things Stick on the refrigerator doorThey are made of some type of ferromagnetic material, such as iron, nickel, alnico or neodymium. Ferromagnetic materials basically contain areas that act like a single magnet, each area having a north and south pole. If all these magnetic domains are aligned, the material will function like a magnet. (There are some very complicated things at the atomic level, but let’s not worry about it now.)
However, in this case, Wile E. Coyote has an electromagnet that generates a magnetic field through electric current. (Note: We measure current in amperes. Don’t confuse it with voltage. Voltage is in volts.) All currents produce magnetic fields. Usually, to make an electromagnet, you need to wind some wires around a ferromagnetic material (such as iron) and then turn on the current. The strength of the magnetic field depends on the current and the number of loops formed by the wire around the core wire. It is possible to make an electromagnet without an iron core, but the strength will not be so strong.
When a current generates a magnetic field, the magnetic field interacts with the magnetic domains in the iron sheet.Now that iron Also Just like a magnet-the result is that the electromagnet and the induction magnet attract each other.
How about 10 billion volts?
I don’t know how the script for this episode came from, but in my opinion, they have a group of writers working together. Maybe someone came up with the idea of electromagnets and iron carrots, and everyone agreed to put it there. Someone must raise their hand and say: “You know, we can’t just make an electromagnet. It must be oversized.” Another author definitely replied, “Let’s put a number there. How about 1 million volts?” One person interjected: “Of course, 1 million volts is cool—But what about 10 billion volts? “
What does 10 billion volts even mean for electromagnets? Remember, the most important thing about electromagnets is current (in amperes), not voltage (in volts). To establish a connection between voltage and current, we need to know the resistance. Resistance is a property that tells you how difficult it is to move charge through a wire, measured in ohms. If we know the resistance of the magnet wire, then we can use Ohm’s law to find the current. As an equation, it looks like this: