The second year of science on the question of magnetism

First of all, it is necessary to understand how the north and south poles of a magnet are defined. The end pointing north is the North Pole (N) and the South Pole (S) is the end pointing south. So the question asks you that the magnetosomes in these bacteria are regarded as small magnetic needles, and its n-pole points to **.

The answer, of course, is north.

As for the previous large section of material, it is completely used to interfere with the answer.

When there is only a geomagnetic field and no other magnetic field, some of the bacteria in the small droplets will continue to swim northward and gather at the northern edge of the small droplet. In particular, this passage is easy to mislead people into thinking that the bacteria were sucked to the north due to the magnetic effect, but in fact it is not, note that the word "swim" is used in the title, and the bacteria actively swim over after identifying the direction, rather than being sucked through. In fact, it is impossible to suck it up, unless the bacteria have only one magnetic pole, which is impossible.

The question is profound. But I've just taken the exam.。。。

Moving northward means moving towards the geographic North Pole, and the geographic North Pole is the south pole of the geomagnetic field, that is, the s pole of the geomagnetic field.

Some of the bacteria in the small droplets will continue to swim north" and become "non-stop swimming towards the S pole".

What pole is attracted to the S pole? Common sense.. n pole. Therefore, the understanding that "the small magnetic needle moves north means that the end of the magnetic needle is south" is unreasonable.

At the end of the day, the big chase above is nonsense. You just have to look at the end, "then its n pole points to", n pole. Point to the S pole. The weight options given are all about geography. Otherwise, it's only good for you to go south and north. Understand? Come on, classmates

The north and south poles of the geomagnetic field are the opposite of the north and south poles of geography.

The South Pole of the Geomagnetic Field is located at the geographic North Pole; So the north pole of the small magnetic needle points to the south pole of the geomagnetic field, which is the geographic north pole.

The same poles repel each other, and the opposite poles attract.

The n pole of the magnetic needle will point to the s pole of the geomagnetism (the s pole of the geomagnetic field is equivalent to the north pole of the geography, and the geomagnetic field is the opposite of the north and south poles of the geography). So its n-pole points to the geographic North Pole, yes.

There is a sentence in the textbook: when a small magnetic needle is stationary, the direction of the n pole is the direction of the magnetic field at that point.

The earth is also a magnetic field, the north pole of the geomagnetic field is near the south pole of the geography, the south pole of the geomagnetic field is near the north pole of the geography, and the magnetic inductance lines depart from the n pole of the magnetic field and return to the s pole.

When the small magnetic needle is at rest, the n pole should point in the direction of the magnetic field, that is, to the south pole of the geomagnetic field, that is, the north pole of geography. Of course, it is not completely coincident, and there is a certain declination.

Every moment of our lives is about magnetism. Without it, we can't watch TV, listen to the radio, and play **; Without it, even the night would be pitch dark.

Although human beings have recognized magnetic phenomena for a long time, it is not until modern times that people's understanding of magnetic phenomena has gradually been systematized, and countless electromagnetic instruments have been invented, such as **, radios, generators, motors, etc. Nowadays, magnetic technology has penetrated into all aspects of our daily life and industrial and agricultural technology, and we have become more and more inseparable from the wide application of magnetic materials.

Since the magnetism of matter can neither be seen nor touched, we cannot directly experience the existence of magnetism through our five senses (hearing, sight, taste, smell, and touch), but people have gradually unveiled its mystery in practice. A magnet always has two poles, one is the n pole and the other is the S pole. A magnet, if sawn from the middle, becomes two magnets, each with a pair of poles.

No matter how small the magnet is, it will always have n and s poles, which means that the n poles and the s poles will always appear in pairs, and it is impossible to make a magnet have only n poles or only s poles.

There is an interaction between the magnetic poles, i.e., the same sex repels each other, and the opposite sex attracts. That is, the n-pole and the s-pole attract each other when they are close to each other, while the n-pole and the n-pole repel each other when they are close to each other. Knowing this, we can see why the compass automatically indicates the direction.

It turns out that the earth is a huge magnet, and its n pole is near the south pole of geography, and the s pole is near the north pole of geography. In this way, if a long magnet is suspended from the middle with a thin wire and let it rotate freely, then the n pole of the magnet will attract each other to the s pole of the earth, and the s pole of the magnet and the n pole of the earth will attract each other, so that the magnet will rotate in the direction until the n pole and the s pole of the magnet point to the s pole and n pole of the earth respectively. At this time, the direction indicated by the n-pole of the magnet is near the north pole of the geography.

If the n pole finally leaves the B terminal, then the B terminal is magnetized by the n pole into the S pole, and the A terminal of the steel needle is the N pole.

That is, the magnetized steel needle: the B end is S, and the A end is N.

So choose B

The magnetic field exists in two ways: around the permanent magnet and the electric current.

The electric current has a magnetic effect, and a magnetic field can be generated around it, which is a natural phenomenon and does not need to be explained = =

As for the permanent magnet, there are electrons moving around the atoms inside the Bi gear return magnet, the current is the directional movement of the charge, and the electrons have a negative charge, so the current is formed around the atoms, and the magnetic field is generated.

This is a sophomore in high school.

The similarities and differences between "simple magnetic phenomena" and "simple electrical phenomena" are listed as follows:

Contents Simple Electrical Phenomena Simple Magnetic Phenomena.

Properties Charged bodies attract small and light objects Magnets attract iron, cobalt, nickel.

Definition An object that can attract small and light objects is called a charged body A magnetic object is called a magnet.

Classification Two charges (+, two poles (n, s)

Interaction: Charges of the same kind repel each other, and the poles of the same name repel each other.

Heterogeneous charges attract each other Opposite-named poles attract each other.

The method of obtaining triboelectric magnetization.

I hope it helps you, and if you have any questions, you can ask them

I wish you progress in your studies and go to the next level! (*

Go straight to the two chapters of the science textbook Magnetism and Electricity and Magnetism.

1.Use it to suck a thumbtack, sucking more means that the magnetism is strong, and sucking less means that the magnetism is weak.

2.with electromagnets.

Suck a small nail and a big nail, if you suck on a small one, it means that the magnetic reed is strong, and if you suck on the small one, it means that the magnetic orange is weak.

3.Because the electromagnet has the magnetism that only exists after the current has entered, there is an ammeter.

Just measure the current of the magnet. The current ** is small in clear magnetism, and the large current indicates that the magnetism is large.

1 Definitely not! 3*10 8m s should be converted into kilometers per hour.

2. It has to be judged by the direction of the magnetic inductance line. First imagine that the Earth is a bar magnet with the n pole in the south and the s pole in the north, right? The magnetic inductance line on the surface of the earth is from the n pole back to the s pole, and the direction of the magnetic inductance line at a certain point is not the point where the n pole of the small magnetic needle is pointing?

That is to say, standing at the geographical North Pole, the direction of the magnetic inductance line is downward, and the small magnetic needle is below the n pole; Standing at the geographical south pole, the direction of the magnetic inductance line is upward, and the small magnetic needle is pointed above the n pole. Do you understand? If you don't understand, just hi me.

1。The propagation speed of electromagnetic waves in a vacuum is 30km s, and if you go 30km in a second, then you will travel 10800km in an hour, that is, 10800km h, but if it is not a vacuum, you must consider the refractive index of the medium.

2。In the geographical North Pole, the direction of the magnetic inductance line is vertically downward, and the small magnetic needle is vertically downward; In the geographical South Pole, the direction of the magnetic inductance line is vertically upward, and the small magnetic needle is vertically upward.

1。In a vacuum it is 1080000000km h.

2。North Pole (nearby). Because the south pole of the geomagnetic field is originally in the north pole (nearby) of the geomagnetic field.

1.The propagation velocity of electromagnetic waves in various media can be calculated by v=c n, where c is the speed of light in a vacuum and n is the refractive index of the medium. (Electromagnetic waves propagate at x 10 8 m s (speed of light c) in a vacuum, less than x 10 8 m s where there is a medium, which is demonstrated by animation.)

Why is the speed of electromagnetic wave propagation less than c when passing through a medium? This is because: when energy travels through a medium, it includes wave energy being absorbed and re-emitted by the atoms of the medium.

This slows down the propagation of electromagnetic waves, which depends on the optical density of the medium. ）

2.The North Pole, the small magnetic needle is indicated by the magnetic field lines, and the N pole indicates the North Pole.