Using a bar magnet to a certain distance from the smaller the quality of absorption of iron, a huge electromagnet can smoke tons of steel starting block, indicating that there are strong magnetic fields are weak, how strong or weak magnetic fields that do? We use magnetic field on the current force – Ampere force to study the magnetic field strength.

2, decided to Ampere force the size of the factors which?

(1) with the current size of the relevant
Magnetic field perpendicular to the direction of electricity straight wire by magnetic force the size of wires in the eyes of the size of current, current, and force big; current small force also small.
(2) and electricity wires in the magnetic field is related to the length
Magnetic field perpendicular to the direction of electricity straight wire by the magnetic force of the size limit electricity wires in the magnetic field is related to the length, wire length, large force; wires short, the small force.
(3) with the wires placed in the magnetic field in the direction of
Maintain the current size and the length of electric wire unchanged, change the wire with the angle between the direction of the magnetic field, when the angle is 0 ° when the wire is not moving, that is parallel to the direction of current and magnetic field without the role of Ampere force; when the angle by as large as 90 ° in the process of increasing wire angles, that is current and the magnetic field perpendicular to the direction, suffered the greatest amp; not parallel or perpendicular to, Ampere force the size of the range between 0 ° and maximum.

3, magnetic induction intensity

L expressed by the length of electric wire, I said that current and maintain the current and the magnetic field direction perpendicular to electric wires suffered Ampere force the size of FIL
That this ratio with B, and B = F / IL. The physical meaning of B as follows: electricity wires placed perpendicular magnetic field the same location, B value remains unchanged; if changes in the location of electricity wires, B value change. Show that the B value is the size of the magnetic field itself, the location of the decision. For the same current and the length of wire, placed in the B position by a large value of Ampere force F is also large, indicating strong magnetic field. B value on the location of the small of Ampere force by F is also small, indicating that the weak magnetic field. Thus we can use the ratio of B = F / IL to express the strength of the magnetic field. It is called magnetic induction.
Definition: magnetic induction B = F / IL
Unit: Tesla, symbols for the T
1T = 1N/A.m
Magnetic sense lines can also be directly reflected in the strength and direction of the magnetic field, magnetic sense of the more dense line, the magnetic induction intensity, and strong magnetic field. If the magnetic induction intensity and direction of all the same size, known as the Uniform Magnetic Field.
In the non-uniform magnetic field, and B = F / IL measuring magnetic induction, the wire length L should be very short, absorbed in the current approximation Magnetic Yangzhong.

4, Ampere force the size and direction of

According to the definition of magnetic induction ceremony, the availability of electricity wires placed at the direction of the vertical magnetic field suffered Ampere force size: B = F / IL