# Magnetic field strength over distance

• Bakatota
In summary, the conversation discusses the effects of distance on the magnetic field of a permanent magnet, specifically the inverse square law. The concept of magnetic monopoles is also mentioned, and a link is provided for further understanding. However, it is noted that magnetic monopoles do not exist and the strength of a magnetic field in a dipole follows an inverse-cube law.
Bakatota
I want to know how does distance affect the magnetic field of a permanent magnet. I have read about the inverse square law and how it could apply to magnetic fields over growing distances, but doing so, I read about monopoles, which is a new concept to me. So, for the time being, I would like a link that explains monopoles and an equation that fulfills my needs for my project.

Thank you.

Magnetic monopoles: https://en.wikipedia.org/wiki/Magnetic_monopole

Magnetic monopoles are essentially the magnetic version of an electric charge. I can charge an object to negative or positive and the field emanating from that object obeys the inverse square law in regards to field strength. Magnetic monopoles would behave similarly, except with a magnetic field instead of an electric field.

However, magnetic monopoles do not exist. You cannot break a magnet into single poles, as the wiki article explains.

In a magnetic dipole, which is what most permanent magnets are, the strength of the magnetic field falls off with the cube of the distance. So they obey an inverse-cube law (1/r3).

## 1. What is magnetic field strength?

Magnetic field strength refers to the measure of the force exerted by a magnetic field on a unit charge or current at a specific point in space.

## 2. How does magnetic field strength change over distance?

Magnetic field strength follows an inverse square law, meaning that it decreases as the distance from the source of the magnetic field increases. This is similar to how the intensity of light decreases as you move further away from a light source.

## 3. What is the unit of measurement for magnetic field strength?

The standard unit of measurement for magnetic field strength is the tesla (T), named after the inventor Nikola Tesla. Another commonly used unit is the gauss (G), where 1 T = 10,000 G.

## 4. What factors can affect the strength of a magnetic field?

The strength of a magnetic field can be affected by the magnitude of the electric current, the distance from the source of the field, and the permeability of the medium through which the field passes. Other factors can include the size and shape of the magnetic source and the presence of other nearby magnetic fields.

## 5. How is magnetic field strength measured?

Magnetic field strength can be measured using a device called a magnetometer, which detects the strength and direction of a magnetic field. The strength is typically measured in units of tesla or gauss, depending on the sensitivity of the instrument.

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