Find a physics master!! Desperate for physics masters!!

Classmate, I am also a freshman in high school, and I thought physics was very simple at first, but then I found that physics was getting more and more difficult and troublesome, and I didn't think much about the ideas on the answers

That's how I worked hard for a semester without direction, (very, very hard!) Unfortunately, it turned out to be so miserable. Failing Physics.

But. At the beginning of this semester, my physics grades have skyrocketed! Do you know why?

In fact, I think that physical difficulty is a psychological effect, as long as you overcome the psychological effect yourself, and no one can estimate the power of the subconscious mind (it is said that a genius like Einstein only uses 2% of the subconscious), you just need to say a word in the mirror every day"Actually, I'm smart, physics is very simple"If you talk every day, and then find the right amount of topics to practice, wow, it won't be long before you become perfect.

In the past, I always thought that science was for talented people to learn, but talented people are not as successful as hard-working people.

As for the physics questions, don't think that you can do all the questions, sometimes you do it for a university professor, and he may not be able to do it, so as long as you get the points you deserve in the exam room, then you win...

The above is a little bit of my experience, make a friend, and improve physics together

q360667701

Good luck on our path to physics.!

Physics, like chemistry, must rely on one's own association and analysis, so that we can grasp the essence, and we must think and analyze more by ourselves. Others can only give you, and the answer department can give you ideas. So come on!!

The second floor is right, it's better to find your classmates or teachers, after all, it's much easier to communicate with them than to rely on text on the Internet. Find a physics expert in your class and ask them to hand it over to you.

Or sell a reference book with a very detailed explanation, which must be more detailed than online communication, and more correct. After all, some people are not sure of the answer, and they go back to be bored.

I wish you to find a sense of physics soon.

Physics is based on feeling The representative of the physics department in my class has helped many students who are not good at physics, but I also found that just by teaching a few questions, they can't improve much at all.

Learning physics is related to reality, physics is very close to life, life should be everywhere to pay attention, you may find that you used to think that things that are more commonplace to think about it is still quite a doorway, don't let your brain always be in a state of rest, to learn to enjoy thinking, good at finding things that others do not pay attention to. For example, when you look at my reply again, have you ever wondered how the screen in front of you works? What is the difference between an LCD screen and a CRT screen?

Why do speakers make sound? It's interesting to think about......

Physicists, enlightened also.

If you have any questions, send them here, there are many enthusiastic people to solve them for you.

Find someone to ask, sometimes he doesn't have time, sometimes he may not know or do wrong, it is better to brainstorm here.

You're not the best idea.

I hadn't studied physics for a long time, but my grades were still good.

Willing to communicate.

That's right for me, we're both freshmen in high school, and I'm very fond of physics.

I'm not a strong man either, but I still know how to order ordinary freshman and sophomore questions, and I'm smiling.

I'm particularly fond of physics.

I have set up a college entrance examination group, 61904652, everyone will be added.

This question relates to the moment of inertia problem in university physics:

Moment of inertia: The mathematical condition of rotation of a rotating body with mass, represented by a letter j=mr(2), which is the product of the mass and the square of the radius.

This mass pulley refers to a mass disc, and its moment of inertia is expressed as: J=1 2*mr(2).

There is also a problem related to the problem of torque, this thing has been exposed to in junior high school, moment = force x force arm.

Regarding the resultant moment of rotating the disc m=f1*r-f2*r, which is the moment of the difference between the left and right forces of the disk.

This quantity m=jb, which is the product of the resultant moment m equal to the moment of inertia and the angular acceleration (b=w t).

This angular acceleration is related to the linear acceleration of the disc is br=a, and the acceleration of the two weights is the same as the linear acceleration of the disk.

Well, with the above reserve knowledge, you can solve this problem.

Obviously, due to the mass pulley, the tension on both sides of the rope is different:

The pull of the rope on the side with a large weight is large f1

The tension of the rope on the side where the weight is small is small f2

Then according to the high school physics knowledge of Niu Er's law connectome solving method, you can solve this problem.

The conditions given in the question are not very clear, but let's assume that the masses are m1

The tensile force of the rope on the lighter object = (the mass of the heavier object - the weight of the lighter object) * the acceleration due to gravity.

The direction of the force is vertically upwards (if the rope is wobbling, it is along the direction of the rope).

It has nothing to do with the quality of the pulley and the speed of the pulley, the pulley simply provides an environment to hang up, and the speed is caused by the forceful action on the rope.

Solution: Since it is a smooth horizontal plane, the force between the wooden block and the car is an internal force, so the momentum of the system is conserved, so there is: mv0 = (m + m) v total, and the solution v total = 5m s.

After putting on the wooden block, because there is a relative motion between the two, the wooden block will be subjected to a forward force to make the wooden block do a uniform acceleration motion, and the car will do a uniform deceleration motion, from the question to know that this force f=mgu=10n, there is Newton's second law f=ma, and the acceleration a=5m s 2 is solved, so there is v total = at, and the solution is t = 1s.

Answer: 3200 turns.

Problem solving process: according to the formula: the number of turns of the primary coil The number of turns of the secondary coil = The voltage of the primary coil The voltage of the secondary coil.

220 55 = x 800 gives x = 3200

1.Inductive circuits can be generated.

2.The high efficiency is lower than that depends on the magnetic flux, the permeability of the silicon steel magnetic circuit and the cross-sectional area of the silicon steel sheet (small area, small eddy current loss, high efficiency).

3. About magnetic flux: The reason why the transformer is not as designed as in your figure, the permeability of silicon steel (electromagnet) is much higher than that of air (vacuum), and the magnetic field diffusion will be much smaller, that is, the magnetic leakage will be very small, the magnetic energy will be large, and the efficiency will be high.

PS: A misunderstanding, the so-called cutting of magnetic field lines is not necessarily the real need for the wire to be cut from one side of the magnetic field to the other, and the wire can pass through the magnetic field line (high school textbooks only talk about cutting magnetic field lines). A more theoretical definition is:

The rate of change of magnetic flux in a closed-loop circuit (the amount of change per unit of time) is proportional to the generated current. Literally, a very small magnet flies through the middle of an O-conductor at a certain high speed, and the current generated can burn the O-conductor because the rate of change of the magnetic flux is too high. The same very large magnet passes through this O-conductor at a very slow (close to zero) speed, producing a current that is so small that it can be ignored.

4. From your diagram, the magnetic flux and the rate of change of the electromagnet (magnetic circuit part) in your coil have remained unchanged (the energized coil remains unchanged, and the frequency of alternating current remains unchanged). Then the efficiency is only inversely proportional to the amount of magnetic flux leakage. If the leakage is zero, the efficiency will be high.

If the wire used in the coil is an electrical superconductor, the silicon steel sheet in the electromagnet is a magnetic superconductor, and the secondary coil is also an electrical superconductor, then congratulations, the efficiency has reached 100%.

Note: In practice, it can never be 100%, let alone exceed... Otherwise, 2012 is really coming, imagine that if you input 1J of energy and produce 2J of energy output, then use this 2J input to produce 4J of output.

Is this just 2012? The universe burned down.

5.Be careful when playing with fire. For everyone's sake.

6. You can do 50% of this, which is considered a very high level.

In fact, there is no need to cut the magnetic induction wire, and the same induced current can be generated. Because the electromagnet is powered by an alternating current, the magnetic field generated is constantly changing, and an induced current is generated in a closed coil in a changing magnetic field.

Also, the formula of Faraday's law of electromagnetic induction is: e=n*d dt, where e is the induced electromotive force, which is the voltage induced, n is the number of ties of the coil, is the magnetic flux of the magnetic field, and t is the time. d dt stands for the rate of change of magnetic flux, which can be understood as the faster the magnetic flux changes, the higher the voltage generated.

The resulting power w=e2r=n2*(d dt)2r. That is, the power generated is proportional to the square of the number of coil ties, directly proportional to the rate of change of the magnetic flux, and inversely proportional to the resistance of the coil.

Regarding magnetic circuits and magnetoresistance, I don't talk about physics majors in college anymore, and I really can't do anything about it. Today's transformers have been designed very well, simple and practical. If you want to improve, you mainly start from the material aspect. Finally, to encourage the innovative spirit of LZ.

If the theory is linked to the practice, let me give you an example, you will understand that this diagram can be compared to the welding machine we use.

They are 1st and 2nd winding.

As for what they say, there must be magnetic flux leakage, but the proportion is not large.

Isn't it efficient??

Don't drill the horns!!

If we adjust the distance between the two coils, the magnetoresistance will change, and the current size of the second side will be changed, and the copper and iron losses of such circuits will inevitably exist.

Combined with the actual situation, if you do more than 95% well, there is no problem, if you are free, ask the master who does electric welding, and you will be more satisfied with the answer!!

Your question is very good, according to the diagram you designed, combined with Faraday's law of electromagnetic induction, after the other coil of the iron core is passed through the alternating current, it can generate a periodic magnetic field, but because the secondary coil is not completely inserted [it cannot be on one side, but the gap between the core and the secondary coil should be completely orthogonal], so it can only produce a weak current, and the efficiency is naturally not high. In addition, the solution you improved is not very ideal. All you need to do is move the coil inward so that the core opening intersects the center of the coil perpendicularly.

Hope it helps.

You shouldn't cut a section of the transformer core at all, so that a flux circuit becomes an inaccessible circuit.

Doing so will burn the coil.

1. It can generate electric current. Because there is still alternating magnetic flux flowing through your closed circuit.

2. The efficiency will not be high (compared with not cutting the core). Because of the increased air gap, the magnetic resistance of the magnetic circuit increases; The alternating magnetic flux flowing through the closed loop is also reduced (because you put one of the wires of the loop between the core gaps, and there is also a "leakage flux" outside the closed loop), which determines that the device is inefficient.

Look at your opening and let another wire get stuck in it, so that the induced current will not be in the circuit you insert, but in the small section of the conductor that is inserted into the opening, it is the small conductor that is hot, and it is very powerful.

Is it possible to generate current in a closed coil?

Flow**? Will the current still spin in circles?

Even if you don't cut it, you can generate an electric current.

There is an alternating magnetic field flow within the core of the transformer.

An alternating magnetic field produces a toroidal closed alternating electric field in the direction of orthogonal (perpendicular to it).

This means that if you put a piece of conductor, as long as the plane of the conductor is parallel to the plane of the electric field, it will be on both sides of the conductor to the alternating voltage.

This is the same principle as using electromagnetic wave communication to receive signals.

The so-called cutting of magnetic inductance lines is actually to change the magnetic flux through a closed circuit, and your magnetic field is alternating, and even if you don't cut it, the magnetic flux that passes through will change, and the electric field will change, and if you put a closed circuit in the electric field, the carriers (free charges) in the circuit will move under the action of the electric field to form an electric current.

The electric field is independent of each other, and even if you don't have a conductor anywhere, there's no electric current.

I think so:

It must be able to produce induced current, but there is no need to cut at all, because the magnetic field itself at the fracture is also changing, as long as it is surrounded like the figure provided by log6262635, it can generate current, if you have to cut, then the cutting frequency is appropriate (the magnetic field becomes small to the right, and when it becomes stronger, it should be able to increase the rate of change of magnetic flux, but cutting requires external force to do work, and the power generation should be less than the work done by external force, which is not cost-effective.

Looking at the diagram provided by log6262635, it is equivalent to an ordinary transformer, and due to the fracture, the magnetic field strength will be greatly reduced and dispersed, and the efficiency will be very low.

As for superconductivity, if superconductivity is successfully developed, we still need transformers...

Just a personal opinion ang.

It will definitely be able to generate induced current, but the efficiency may not be ideal.