Is magnetic force an external force

1. Ampere force F = iblsin α
Lorentz force F = QVB

2. Just remember the conservation of energy. When the external force works in the magnetic field, part of it generates electric current and heat. Part of it becomes kinetic energy, if any

3. First of all, the problem of "external forces". I suggest you stop worrying about whether a certain force is an external force. When we analyze the force on an object, any force exerted on it is an external force, and there is no difference. Including gravity, friction, pull, thrust, electric field force, Lorentz force, etc.
in addition, the force analysis of an object, the result of force analysis, is the direction and size of resultant force. When the force is balanced, the resultant force is 0.
finally, we analyze the force to know what the force has done? In high school physics, what force actually does is to change the motion state of objects. The so-called motion state, the main description index is the speed and displacement. To think about the function of force from another angle is whether force has done work
now let's look at the Lorentz force. This force is always perpendicular to the direction of motion of the charged particle, so it does not change the magnitude of the velocity, only changes the direction of the velocity. So this force does not work. And this force will act as the centripetal force of the electron in the magnetic field, making the electron do uniform circular motion in the magnetic field. The kinetic energy of the electron remains unchanged, and the mechanical energy of the electron remains unchanged when gravity is ignored and there is no electric field
after knowing these, we will see what the topic asks you to do to make a concrete analysis

4. The force of magnetic field on current is called ampere force, which may be the force of magnetic field on magnetic pole. Therefore, Ampere force is a kind of magnetic force, so magnetic force is not equal to ampere force.

5. Not counting, Ampere force: it can be expressed as a straight wire of length L with current intensity I and placed in a uniform external magnetic field with magnetic inction intensity B, then the ampere force on the wire is f = iblsin α， Where α Is the angle between the current direction and B direction in the conctor, and the units of F, l, I and B are n, m, a and t respectively. The magnet is not a closed circuit, and there is no current, which does not conform to the principle of Ampere force. The effect of magnetic field on magnet is that the same sex repels each other and the opposite attracts each other.

6. Overcoming the magnetic force to do work means that the magnetic force does negative work
in high school physics, a force is often used to do negative work,
it is said that an object overcomes the force to do work,
for example,
the resistance does - 3j work on the object,
it is often said that the object overcomes the resistance to do 3j work.

7. Suppose a coil is in a magnet, with the N pole on the left and the S pole on the outside. The coil near the N pole is marked as side a, and the coil near the S pole is marked as side B. When the magnet rotates anticlockwise, the magnetic field generated by the magnet penetrates into the coil, that is, it is inward for the coil. According to Lenz's law, the inced current always hinders its increase. Use the right-hand spiral to judge that the current generated by side a is down along the wire, and use the left hand to judge that ampere force a is right (it's not right, how to say it looks like it's pulling outward, and it's marked as right). In the same way, judge that the current on side B goes up along the wire, and according to the left-handed ampere force B to the left (it seems to pull in and mark it as if it is left). So the coil turns counterclockwise, in the same direction as the magnet
if the magnet rotates clockwise, the magnetic field generated by the magnet will pass through the coil. In the same way, the left hand rule is used. If only one quantity is changed, the stress on the conctor will be reversed. If two quantities are changed at the same time, it can be understood that the direction of the force is the same as the original direction
please adopt!

8. Magnetic force
includes Lorentz force of magnetic field acting on moving charge and Ampere force of magnetic field acting on current<

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Introction

explanation
magnetic force includes Lorentz force of magnetic field acting on moving charge and Ampere force of magnetic field acting on current. Ampere force is the macroscopic expression of Lorentz force. Magnetic force phenomenon involves three physical quantities: magnetic field direction, charge movement direction and Lorentz force direction; When we use the left-handed rule to explain the direction of the three physical quantities, we have a premise that the direction of the magnetic field is perpendicular to the direction of the charge movement or the direction of the magnetic field is perpendicular to the direction of the current, This view is not correct.

the fact is that the direction of the magnetic field is not necessarily perpendicular to the direction of the charge motion or the direction of the current, and the angle between them can be arbitrary, The Lorentz force is perpendicular to the plane determined by the magnetic field B and the velocity V of the charge. The ampere force must be perpendicular to both the direction of the magnetic field and the direction of the current. The ampere force is perpendicular to the plane determined by B and I. We should not ignore an important fact: when B is parallel to V or I, neither Lorentz force nor ampere force exists.

therefore, when B ⊥ V or B ⊥ I, When B and V or B and I are not perpendicular, the direction of Lorentz force f or ampere force F can be determined according to the direction of B and V or the direction of B and I, but the direction of B cannot be determined only according to the direction of V and f or the direction of I and F; The direction of V or I cannot be uniquely determined according to the direction of B or f or the direction of B or F. if there is a uniquely determined solution to these two problems, the conditions must be supplemented.

b = f / IL (B ⊥ L)

B has nothing to do with F, I or L<

F = mg.

classification
there are two kinds of magnetic force, one is the force of magnetic field on electrified wire, the other is the force of magnetic field on moving charge.

9. In fact, the magnetic field is an abstract existence, and the magnetic field line we usually use is also created by scientists for convenience. The field is invisible and cannot be forced naturally. In fact, the object in the magnetic field will be forced by the magnetic field. My answer may not be absolute, because it may interfere with the deeper knowledge of physics, which may be explained by physicists

10.

1. According to different definitions,

magnetic force is a kind of force, which includes the force of magnetic field on electrified wire and the force of magnetic field on moving charge

The ampere force is the force exerted on the concting wire in the magnetic field

The magnetic force includes Lorentz force of magnetic field acting on moving charge and Ampere force of magnetic field acting on current. The ampere force is part of the magnetic force

The direction of magnetic force may be perpendicular to the direction of motion, or perpendicular to the plane determined by the electrified wire and the direction of magnetic field

The direction of the ampere force is perpendicular to the plane determined by the direction of the concting wire and the magnetic field, and the direction between I, B and F is determined by the left-handed rule