What are the confusing electrical concepts in sophomore physics?

1. Free electrons and free chargesFree electrons refer to electrons that are free from the bondage of atomic nuclei, and free charges can be free electrons, positive and negative ions. The free charge in the metal conductor is free electrons, and the free charge in the aqueous solution of acid, alkali and salt is mainly positive and negative ions.

2. Charged and conductive charged means that the object loses electrons or gains excess electrons, so that the object becomes externally electrically charged. Conductivity means that there is an electric current in the conductor, and its essence is that there is a large number of free charges in the conductor for directional movement.

3. Objects that are easy to conduct electricity by conductors and insulators are called conductors. Objects that do not easily conduct electricity are called insulators. Conductors are easy to conduct electricity because there is a large amount of charge inside the conductor that can move freely, whereas insulators are not easy to conduct electricity because there is almost no free charge inside the insulator.

There is no absolute boundary between conductors and insulators, and they can be converted into each other under certain conditions. For example, glass is a very good insulator at room temperature, but when heated to a red-hot state, it becomes a conductor.

4. Conductors and wire conductors refer to objects that are easy to conduct electricity. The wire refers to the wire made of metal with good conductivity, which is generally used to connect circuit components to form a circuit, and the resistance of the general wire is very small and often negligible.

5. Electroneutrality and electroneutrality refer to a state in which the positive charge carried by the nucleus and the total negative charge carried by the electrons outside the nucleus are equal, and the whole atom is not electrically external. Electrical neutralization refers to a process whereby when two objects with an equal amount of heterogeneous charge come into contact with each other, the excess electrons on the negatively charged object are transferred to the positively charged object, thus restoring both objects to an uncharged state.

6. Power supply and voltage power supply refer to a device that can provide continuous current, or defined as a device that converts other forms of energy into electrical energy. The function of the power supply is to continuously make the positive electrode accumulate positive charges and the negative electrodes accumulate negative charges inside the power supply to continuously supply voltage to both ends of the circuit. Voltage is what causes the charge to move directionally to form an electric current.

Because the voltage at both ends of the circuit is provided by the power supply, there must be a power supply in the circuit to have voltage, and then a continuous current can be obtained.

7. The amount of electricity and current charge is called electricity, and the unit of electricity is coulombs. The amount of electricity carried by an electron is a coulomb, which is called a meta-charge. The directional movement of the charge forms an electric current, and the magnitude of the current can be expressed in terms of the amount of electricity passing through the cross-section of the conductor in one second.

This topic is a bit "big"! Can you be specific?

1. Mechanics and electricity are the two most important parts of high school physics, and the difficulty of physics is not electricity or mechanics, but the combination of electricity and mechanics.

Second, junior high school electricity in high school is reflected in the knowledge of series and parallel, this when you learn electricity, your teacher will re-teach you, you will listen carefully and find that it is very simple.

3. I don't approve of preview, which will discourage the enthusiasm of class, if your teacher's class is really boring, just preview, preview is mainly to read the textbook carefully by yourself slowly (pay attention, is slowly), the textbook is carefully written by experts, and it will not be too difficult to understand. If you really don't understand something, you have to listen carefully in class.

Fourth, the information book? If you feel that physics is weak, you have to buy it, and the key to the transformation of a good student is to get the same sense of the question as a good student by brushing the questions, which you can experience yourself.

Don't be afraid, even if you don't do well in junior high school, it won't have much impact on your high school. Study hard, no problem! You don't need to buy a textbook, but you must read the textbook definition carefully, and understand that it is not good to get in touch with the information too early, and if you really want to buy it, just look at the above knowledge points.

Personally, I think it's useless to prepare, you have to listen to the teacher, you haven't learned well in junior high school, and you can't understand it even more when you look at high school, you have to understand every class in high school, and if you don't understand, you have to ask immediately, and you can't keep up with the next section of content, it's more difficult in high school, mechanics is difficult, and electricity and magnetism will be connected, and it's not simple.

The electric field strength is analogous to the magnetic field strength, and there is also a magnetic induction strength, which needs to be distinguished separately.

The capacitor is an internal medium, and in fact, it can be thought of as a resistor with a very large resistance, so it is directly connected to the battery, and there is a weak current passing through it (the simple principle of comparing voltmeters).

Since the resistance value and current are determined, of course, the voltage between the two plates remains the same, and the voltage is the external manifestation of the potential difference, compared to the electromotive force of the power supply, if the wire is uniform, it is an equipotential body, because the electric potential of each part of the wire is equal, imagine the wire as an infinite number of resistors with the same resistance value, the same current, and the voltage distributed is equal everywhere.

So wires are equipotential bodies.

The part connected by the conductor is equipotential, and the wire is also a conductor, so the wire is also equipotential, but the positive and negative poles of the battery have potential differences, so the two sides are different potentials.

Wires are considered equipotential. However, the voltage cannot be said to be the potential difference, it can only be said to be numerically equal, and the potential difference is positive and negative.

The voltage between the two boards is the voltage of the battery, and the capacitor is equivalent to the voltmeter!

For the first question, there is no problem with the formula you are thinking, the bigger the i, the hotter and more dangerous. But for rice cookers, the rated power and rated voltage are both certain, that is, the rated current is also certain. In the question, it is found that the conductor of the terminal board has obvious heating phenomenon, which means that the current of the previous terminal board is greater than the rated current.

So replace. For the second question, your analysis is q=u 2 r*t (where u,t is the same) and p=u 2 r (which means r is the same.) Doesn't that mean, q?

In fact, the range of application of q=u 2 r*t is pure resistive circuits. Most of the electric energy of the electric fan is converted into kinetic energy, the fluorescent lamp is the current through the tungsten filament to make it red, the bulb is shining, the electric soldering iron is mainly to melt something, so all the electrical energy of the laughing zen is converted into heat energy. Therefore, the voltage shared by the resistor is different, and the dust Q is also different.

A clever answer to a question: the maximum current of each circuit board is limited, and excessive current will cause the temperature of the circuit board to rise and burn out.

Answer to the second question: Most of the electric energy of the electric fan is converted into kinetic energy, the fluorescent lamp is the current through the tungsten filament to make it red, the bulb is glowing, and the soldering iron is mainly to melt something, so all its electrical energy is converted into heat energy.

Question 1, the power strip I is almost unchanged. r becomes smaller, so the heating phenomenon is eliminated.