# Strenght of magnetic fields on magnet

• KyoPhan
In summary, the conversation discussed the use of a bar magnet and a device for measuring magnetic fields in lab. The device was used to measure the north and south poles of the magnet, resulting in measurements of 9T and 75T, respectively. The expected value for the south pole was -9T, but the measurement was significantly higher. The conversation then delved into questions about the range and construction of the measuring device, as well as the size of the magnet and its poles. It was suggested that the device used was a Hall probe, which can measure the axial and transverse components of the magnetic field. Finally, an analogy was given to explain why the measurements at the two poles did not change in sign.
KyoPhan
In lab, we used a bar magnet and a device that can measure magnetic fields. We put the measuring device near the north part of the pole and it measured 9T. We did the same to the south, but it gave us 75T. I was expecting it to give somewhere around -9T, is that what is suppose to happen? We repeated the process, but it still gave us the same values.

Can someone help me understand what happened? Thx

It should be the same at the two surfaces, but near the surface, the field is so high that something else may be going on. What is the specified range of measurement for your measuring device? How is it constructed? Did you make measurements at, say, 1cm intervals for the 10cm area above each pole? How do those measurements compare? How big is the magnet and its poles physically?

Er i don't know much about it. The shape was kinda like a gun where at the tip, it can measure magnetic fields in two ways. It can be by axial and i forgot what the other one was called. When we measured it it was about 4 cm away from the magnet. We did the same distance for both poles but we got some weird value.

It probably was a Hall probe.

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/hall.html#c3"

There are usually markings on the probe that enables one to hold it such that the magnetic field is perpendicular to the conducting plate. Some probes have two perpendicular plates. One is held perpendicular to the direction of the bar magnet. This will then measure the axial component of the magnetic field - in the direction of the axis of the bar. The other plate is perpendicular to the first and it measures the the transverse component of the magnetic field. To get the strenght of the field one therefore need to combine these two components.

If you did not observe the orientation of the probe, that is you rotated it about its own axis as you measured the two different poles, the two readings would be different at the two poles.

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Point your index finger away from you. Hold the palm of your hand up against it. The finger represents one magnetic field line coming from one of the poles of the bar magnet. The palm of your hand is the conducting plate of the hall probe. The magnetic field line goes throught the plate and loops around and entering the magnet on the other side. If you loop your finger like that you will see that it points in the same direction again, meaning that if you held the hall probe up against the other pole the magnetic field will cross it in the same direction. This will then induce an electric potential in the same direction over the plate in both cases. That is why the sign of the measurement do not change at the two poles.

## 1. What is the unit of measurement for the strength of magnetic fields?

The unit of measurement for the strength of magnetic fields is Tesla (T).

## 2. How is the strength of a magnet's magnetic field measured?

The strength of a magnet's magnetic field is typically measured using a device called a magnetometer, which can detect and quantify the strength of a magnetic field.

## 3. What factors affect the strength of a magnet's magnetic field?

The strength of a magnet's magnetic field can be affected by several factors, including the material the magnet is made of, the size and shape of the magnet, and the presence of other magnetic fields nearby.

## 4. Can the strength of a magnet's magnetic field be increased?

Yes, the strength of a magnet's magnetic field can be increased by increasing the amount of electric current flowing through the magnet or by adding additional magnets together to create a stronger combined magnetic field.

## 5. What are some real-world applications of strong magnetic fields?

Strong magnetic fields have a wide range of applications, including use in medical imaging devices such as MRI machines, in generators and electric motors, and in magnetic levitation systems for high-speed trains.

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