[Science] Magnetic Force Created by Electric Current (5th Grade) ~The Secret of Electromagnets~
Hello, everyone! Today, let’s learn about the "magnetic force created by electric current" together.
When you hear the word "magnet," you might think of the ones you use when playing in the sandbox or the magnets that hold papers on the refrigerator. But, believe it or not, you can actually create a magnet using "electricity"!
This is called an "electromagnet." It might seem a little difficult at first, but it becomes very interesting once you understand how it works. Let's take it slow and get started!
1. What is an Electromagnet?
An electromagnet is something that becomes a magnet when an electric current flows through a coil of wire.
Unlike regular magnets, the big feature is that it only acts as a magnet while electricity is flowing through it.
What you need to make an electromagnet
・Coil: A wire wrapped around many times.
・Iron Core: An iron rod placed inside the coil. Putting this in makes the magnetic force much stronger!
・Battery and Wires: Necessary to make the electricity flow.
[Fun Fact] Why use an "iron core"?
If you run electricity through just the coil, a magnetic force is created, but it’s very weak. By putting an iron rod inside, the iron focuses the magnet's power, transforming it into a strong magnet!
Key points so far:
An electromagnet only becomes a magnet "when electricity is flowing"!
2. Let’s investigate the "Poles" of an electromagnet
Just like a regular magnet, an electromagnet has a North Pole (N-pole) and a South Pole (S-pole). However, electromagnets have a "special talent" that regular magnets don't have.
Changing the direction of the current switches the poles!
Try flipping the direction of the battery to reverse the direction of the electric current. You’ll notice the needle of the compass points in the opposite direction.
In other words, "when you change the direction of the current, the N-pole and S-pole of the electromagnet switch!"
[Common Mistake]
People sometimes assume that adding more batteries changes the poles, but that’s not true! The only thing that changes the poles is changing the "direction" of the current.
★ A tip for remembering:
"If the direction of the flow changes, the face (pole) changes too!"
3. How do you make an electromagnet stronger?
How can we boost the power of an electromagnet to pick up more paperclips? There are two ways to do this.
① Increase the current
Connecting two batteries in a "series circuit" increases the current that flows through the wire. The larger the current, the stronger the magnetic force becomes.
(*Note: In a parallel circuit, the amount of current doesn't change, so the strength stays about the same.)
② Increase the number of coil turns
Try wrapping the wire more times. For example, 200 turns will create a stronger magnetic force than 100 turns.
[Rule of Thumb]
・More Current (Batteries) = Stronger Magnetic Force!
・More Coil Turns = Stronger Magnetic Force!
Point:
"If you want it to be stronger, use more electricity or wrap the wire more times!"
4. The difference between an electromagnet and a regular magnet
Let’s summarize how useful electromagnets are. Compared to regular magnets (permanent magnets), there are three convenient advantages:
1. You can turn it on and off with a switch! (When you cut the electricity, it goes back to being just a piece of iron.)
2. You can change the strength! (You can adjust it by changing the current or the number of turns.)
3. You can change the poles! (Just flip the direction of the battery.)
"It might feel difficult at first, but once you understand these three differences, you're almost an electromagnet master!"
5. Electromagnets in our daily lives
Electromagnets are used all around you. The most common example is the "motor."
How a motor works
Inside a motor, there are electromagnets. By running a current and using the "repelling force" (N to N, etc.) and "attracting force" (N to S) of the magnets, it turns the inner rotating part. From toy cars and electric fans to washing machines and electric vehicles, motors (which are electromagnets) are used in many things that move.
Large Cranes
In recycling plants that collect scrap metal, there are cranes equipped with giant electromagnets. They turn on the electricity to make the iron stick to the crane, move it, and then cut the power so the iron falls exactly where they want it to go. It’s so convenient!
Summary: Just remember these!
・An electromagnet becomes a magnet only when electricity flows through the coil.
・If you reverse the direction of the current, the N-pole and S-pole will switch.
・Increasing the "current" or the "number of coil turns" makes the magnetic force stronger.
・They are used in essential tools in our daily lives, like motors.
Great work! Electromagnets are like magic devices that connect invisible "electricity" and "magnetic force." Try playing with an experiment kit, and you'll understand it even better!