Problems of physical electricity in the first year of junior high school, and problems of physical e

The role of the battery is to create an electric field along the wire, which generates an electric current through the wire. Energy is required to maintain the electric field. Besides, electric current is also a manifestation of electrical energy!

Energy can't always be generated for no reason, so the battery is to replace chemical energy (energy produced by chemical reactions) with electrical energy.

To give an inappropriate example, if you lift a heavy object and do not move, according to physics, you are not doing work on the object, but you still feel very tired and need to replenish your physical strength!

Oh, you go and ask your teacher if he is going to be praised ......

The current is the same, the battery is chemical energy, after the switch of the access circuit is closed, the chemical energy will be converted into internal energy, and heat will be generated in the conversion process, so in the conversion process of chemical energy, the converted chemical energy is greater than the converted electrical energy. (The transformation of this energy you will learn in the third year of junior high electricity), in addition to the electrical energy consumed by the electrical appliances in the circuit. The electrical energy that is converted from chemical energy is converted into other forms of energy...

Little by little, the chemical energy will be consumed, so the battery will run out.

Whew, a little tired...

Something must have a power, the battery is the power that pushes the current flow, and when the power is used up, there will naturally be no power.

Is there still physics in the first year of junior high school? It's all been there since the second year of junior high school, right?

I think this has to be explained by the essence of resistor generation:

The formation of electric current in the conductor by free electrons is the result of their directional movement under the action of voltage, and in the process of directional movement, the movement of electrons is affected by some other factors, such as the thermal motion of electrons, because any particle has to do thermal motion when the absolute temperature is not zero, and this thermal motion is irregular, and directional movement has an obstructive effect. Therefore, the resistance of the conductor varies with the time of energizing i.e., temperature. It can't just be about the material, the length, the cross-sectional area.

In addition, electrons are subject to the average hindrance of a large number of nuclei, the hindrance between electrons, the collision between electrons, the collision between electrons and nuclei, and so on. Of course, some of the various obstacles have a larger impact and some are smaller, and these microscopic impediments form a resistance at the macroscopic level.

However, there are countless electrons in the conductor, and the influence of each is large and small, and some unimportant factors such as temperature, cross-sectional shape of the conductor are often ignored for the sake of convenience in the calculation process. Therefore, within the scope of the landlord's involvement, there is no need to consider these factors, otherwise many things cannot be quantitatively calculated.

Of course, it's also very good for the landlord to recognize these o(o,I hope you can know some things in essence.,But don't get into the horns of the horns in learning.。

The same, no matter what kind of shape, as long as the area is the same, the resistance is the same.

In the opinion of the upstairs, resistance does not refer to the time it takes for an electron to travel through a certain section of wire, but rather a quantity like friction.

It's the same, this is calculated according to the formula, some things can't be based on your own feelings alone, but some things are still related to feelings, but it's not this problem

The conduction of metals is not determined by the length of the distance, but by the energy bands of the metal crystals. This involves the question of the energy band, valence band, and conduction band of the crystal. If the landlord is interested, you can go down.

In short, it has something to do with the transition of energy.

Well, as long as the area is the same, the resistance is the same, because his total area has not changed, but the shape has changed

The same. You can't feel it.

1、p=u²/r

r=u²/p

r1=220²/40=1210 ω

r2=220²/10=4840 ω

r total = r1 + r2 = 6050

2. After series connection, it is also connected to the 220V circuit.

i=u r=220 6050=

3. P total = ui = u r total = 220 * 220 6050 = 8w

Lamp resistance R1 = 220 40 = 1210 "220V, 10W" lamp resistance R2 = 220 10 = 4840 (1): Total resistance r total = 1210 + 4840 = 6050 (2): total current i total 220 r total

3): Total power p total i total r total

The total resistance is 6050 ohms, the total current is equal to the voltage at both ends divided by the total resistance, and the total power is equal to the voltage multiplied by the current.