Magnetism

Magnetism

By Muhammad Arief Kurniawan

​Magnet

​magnets have two poles. As seen in the picture,
N represent North; and
S represent South.

In general way, we can translate the poles into
positive pole and Negative pole.

Drag and Drop

When two magnets are brought close together, there is a​

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between them. The north pole (N pole) of one will ​

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the south pole (​

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) of the other. Two ​

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will repel each other and two south poles will ​

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each other.

Drag these tiles and drop them in the correct blank above

force

attract

S pole

north poles

repel

positive

negative

​Magnetic Materials

​Compass needle is a permanent magnet. It is made by hard steel.

​Other magnetic material called ferrite.

​Steel and ferrite made by chemical element called iron (Fe). Other magnetic elements in periodic table are nickel (Ni) and cobalt (Co).

​Induced Magnetism

​When a magnetic material is only magnetised when placed in a magnetic field.

Since the nail is made from magnetic material but not magnetised yet, when we put the nail closed to the magnet, suddenly it will magnetised and also has poles like in the picture.

Open Ended

How inducing magnetism can help us in house work? (check the image)

​Magnetic Field

​We interpret magnetic field with lines, magnetic field lines.
The direction of the field is important to know: Magnetic field comes out of north pole. and go in to south pole.

The closer the lines gap, the stronger the magnetic field.

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​Electromagnets

​Electromagnet is an advance thing to magnetise materials.

We use electricity to make magnets. and from the magnetised materials we will create movement (force of attract or repel from magnetic field).

​We will use a special tool for electromagnet made by coil of copper called solenoid.

​How electromagnet works?

​We need electricity (electric current) to flow in the wire (solenoid). In this case, the electricity comes from the battery.

After electricity connect, the solenoid will become a temporary magnet with magnetic field around the coil, and the energy will convert to movement energy (force from kinetic energy) to launch other magnetic material like in the picture.

Multiple Select

In permanent magnet we cannot change the strength of the magnetic field. But in electromagnets, we can increase the strength of the magnet. Which answers are correct?

• Increase the current flowing through it. (for example by changing the battery into more powerful battery)

• Increase the number of turns of wire on the coil.

• Add a soft iron core