Physical electromagnetic problems, a physical electromagnetic problem?

The problem is that the functional relationship has little to do with the magnetic field! Except for the origin, only gravity is provided in the up and down directions, and the Lorentz force does not do work! Uniform:

When the small ring passes through the boundary, the magnetic field changes inside the ring, and the ring generates an electric current, which is then converted into heat energy! After a few times a, it will reach a relatively stable state, and there is no energy loss in orbital motion below a! The energy loss is:

b-a)*mg=w non-uniformity: the magnetic field in the ring changes at all times, and there is a current at all times unless the small ring is stationary! When the rings are stationary, they are definitely at the very bottom!

I can balance the power of the up-and-down direction! i.e. BMG=W

When the magnetic field is uniform. At this point, the small metal ring moves on an orbit with a height of a from the vertex. The velocity is finally 0, and the work done by gravity mg(b-a)mg(b-a)—e=magnetic field is non-uniform magnetic field, the mechanical energy is reduced at all times, and finally it is stationary at the bottom e=mgb+1 2mv 2-0=mgb+(1 2)mv 2

The magnitude of the average induced electromotive force is equal to the rate of change of the total magnetic flux versus time. In the question, the magnetic induction intensity is Tesla, the cross-sectional area of the coil is 27*10-4, and the number of turns of the coil is 19, so the total magnetic flux is 19*, then the average induced electromotive force is equal to the rate of change of the total magnetic flux, that is, the total magnetic flux divided by time: divided by equal. Hope.

According to Faraday's law of electromagnetic induction, electromotive force: e=n t=n( -0) t=nbs t=19

I think A, B, and D should be chosen

If it is known that it is a circular motion with a uniform velocity, then the resultant force must be perpendicular to the direction of v and the magnitude is exactly equal to the centripetal force. Therefore, the gravitational force and the electric field force are balanced, and the direction of the electric field force is upward. Radius of motion r=mv qb

Again. mg=qe

v=sqr(2gh). b right.

Since the electrostatic field is a conservative position, w = -δep

The electric field force does negative work.

The electric field energy can be increased because the gravitational force and the electric field force are equal in magnitude and opposite directions, and the work done is only zero (or from the energy point of view).

e=ep+ek=c

Constant. Unchanged.

And the ek has not changed.

Therefore, EP remains unchanged).

The situation in the 3rd is similar to that in the 1st s, the magnitude of the induced current is constant because the rate of change of the magnetic field is constant per second. Refer to Lenz's law, Faraday's law of electromagnetic induction. The right-hand spiral rule induces a counterclockwise current, and the left-hand rule determines that the direction of the force is directed toward the center of the circle.

The answer is B

1. The principle of the generator: a part of the conductor of the closed circuit is used to cut the magnetic inductance line in the magnetic field. An induced current is generated in the conductor.

It's too inconvenient to explain in detail in words.

There are a lot of questions, these are more basic questions, you go to the schematic diagram of the generator to see more to understand, don't know how to ask classmates, the commutator as the name suggests is to change the direction of the alternating current, so that the current can always flow out from one direction.

Physics questions on the motion of charged particles in the electromagnetic field are hot topics in the college entrance examination, and almost all of them have such questions in the college entrance examination papers every year, and most of them are large-scale calculation questions and comprehensive questions.

Why is the physics question on the motion of charged particles in an electromagnetic field a hot topic in the college entrance examination? Because in order to test so many knowledge points of high school physics in a limited period of time with limited topics, it is necessary to test several knowledge points through a topic, that is to say, the topic should be comprehensive, and the physics questions with the motion of charged particles in the electromagnetic field as the theme can examine the electric field, electric field force, acceleration, velocity, displacement, uniform motion, uniform acceleration motion and magnetic field, Lorentz force, circular motion, centripetal force, centripetal acceleration, linear velocity, angular velocity, geometric drawing, mathematical calculus and many other knowledge points, so, Physics problems on the motion of charged particles in an electromagnetic field are easy to make comprehensive problems.

What you have to do is clear your mind. In fact, the steps of solving each big problem are similar, and you can form a fixed template. Which step to do first, which step to do later.

You have to know this. Moreover, there are only so many knowledge points about electromagnetic fields. I'm sure you know more or less about the classic question types in this area.

Answer: A. When AB moves at a constant speed to the right, the magnetic field lines are cut uniformly to produce a stable and constant induced electromotive force, and the induced current in the right circuit is clockwise (from A to B).

Since it is a stable induced current, this induced current does not produce an induced current on the left solenoid l, because the magnetic flux of the magnetic field induced in the left solenoid l is constant.

If there is no induced current in the CD, there is no magnetic field force, so the CD does not move.

b. When AB accelerates to the right, the induced current in the right coil increases with time.

l induced current, from Lenz's law, it can be seen that the induced current flows from C to D.

The cd is subjected to ampere force to the left and moves to the right.

When C. Cd accelerates to the left, the induced current on the right flows from B to A. The induced current on the left flows from D to C, and Cd moves to the left.

D. When Cd decelerates to the left, the induced current on the left flows from C to D, and Cd moves to the right.

So, B and D are both correct.

If you don't understand something, please hi me. ₁

Needless to say, if a is incorrect, there is no magnetic flux change is impossible to have induced current, analysis b, first of all, you have to understand that the energized rod is the left-handed rule, the energized spiral is the right-handed rule, these understand, the right magnetic field is from the inside out, the rod moves to the right, the left-hand rule, judge the current pointing to a, right, the spiral right-hand rule, thumb down, prove that the magnetic flux is downward, because it is an accelerated motion, the magnetic flux is increasing, then L2 must be up, L2 is right-handed rule, thumb up, The current is C pointing to D, the magnetic field on the left is from the outside to the inside, the left hand rule, the four fingers point to D, then the thumb must point to the right, B is correct, on the contrary, C is definitely not right, then D, the same way, it's just that the magnetic flux of L1 is reduced, then the direction of L2 must be the same as L1.

In fact, it is the weakening principle of the induced magnetic field, which is very troublesome to explain, you think that the magnetic flux of L1 is increasing, then L2 will not let you increase, then the n level they form is on the same side, repulsion, you want to decrease, it does not let you decrease, then their magnetic poles, n, s are on the same side, attract.

AB When moving at a constant speed, according to the right-hand rule, the induced current in AB is constant, the magnetic flux in L1 is unchanged, the magnetic flux passing through L2 does not change, no induced current is generated in L2, Cd remains stationary, and A is incorrect; When AB accelerates to the right, according to the right-hand rule, the direction of the current flowing through AB is A pointing to B, the magnetic flux in L1 increases upward, the magnetic flux in L2 decreases (the obstacle increases), increases, the direction of the current through CD goes downward, CD moves to the right, and B is correct; In the same way, C is incorrect and D is correct. Choose b and d