Magnetic field strength
The overall magnitude of a magnetic field can be measured in units known as webers, abbreviated Wb. A smaller unit, maxwell (Mx), is used if a magnetic field is very weak sometimes. 1 weber is equal to 100,000,000 maxwells. Scientists would use the exponential notation and say that one 1 Wb = 108 Mx. Conversely, 1 Mx = 0.00000001 Wb = 10-8 Wb.
The tesla and the gauss
If you have a certain permanent magnet or electromagnet, you might see the strength of it expressed in terms of webers or maxwells. But usually you will hear units called teslas or gauss. These units are the expressions of concentration, or intensity, of magnetic field within the certain cross section. The flux density, or number of lines per square meter or per square centimeter, is useful expressions for magnetic effects than the overall quantity of magnetism. A flux density of 1 tesla is equal to 1 weber per square meter. The flux density of 1 gauss is equal to 1 maxwell every square centimeter. It turns out so that the gauss is 0.0001, or 10-4, tesla. On the other hand, tesla is 10,000, or 104, gauss.
If you are confused by the distinctions among webers and teslas, think of a light bulb. A 100 watt lamp might emit a sum of 20 watts of visible light power. If you enclose the bulb, then 20 W will fall on the interior walls of the chamber, no matter how small or larger the chamber might be. But this is not a very useful notion of brightness of the light. You know that the single 100-watt light bulb gives light in abundance for a small walk in closet, but it is nowhere adequate to illuminate a gymnasium. The significant consideration is the number of watts per unit area. When we say the bulb gives off x watts or milliwatts of light, it is like saying a magnet has y webers or maxwells of magnetism. When we say that the bulb provides x watts or milliwatts per square meter, it is analogous to saying that a magnetic field has a flux density of y teslas or gauss.
The ampere-turn and the gilbert
When working with electromagnets, another unit is used. This is the ampere-turn represented by At. It is used to measure magnetomotive force. A wire, bent into a circle and carrying 1 A of current, will generate 1 At of magnetomotive force. If wire is bent into a loop which is having 50 turns, and the current stays the same, the resulting magnetomotive force will be 50
If the current is reduced to 1/50 A or 20 mA, the magnetomotive force will go back down to 1 At.
The gilbert is also used to express magnetomotive force sometimes. This unit is equal to 0.796 At. Therefore, to get ampere-turns from gilberts, multiply by 0.796; to get gilberts from ampere-turns, multiply it by 1.26.