Question about the relationship between voltage and current, the relationship between voltage and cu

The current at both ends of the resistance is proportional to the voltage, that is, the higher the voltage, the greater the current, when the voltage is greater than the voltage that the resistance can bear, the resistance will be burned out and the circuit will be broken, and the current at this time is zero. The formula is i=u r. It is the current = voltage resistance.

Current is the product of the combination of the power supply and the closed circuit, and both are indispensable, and it cannot be said that the power supply does not provide current.

High voltage is only a prerequisite for high current, if the voltage is high and the resistance of the closed circuit also increases, the current may not increase.

Ohm's law for closed circuits is a law that comprehensively states the relationship between voltage, current, and resistance: IIR).

ePower supply electromotive force, i.e., open-circuit voltage; r: total resistance of external circuit; r: The resistance within the power supply.

1. Roughly speaking, there is some truth in your understanding in this way, for example, capacitor discharge can be understood in this way.

2. But for the active closed circuit, not only the external circuit has current, but also the internal circuit of the battery. The role of the power supply is to continuously separate the positive and negative charges (with other energy) and maintain the voltage (electric field) in the circuit, which is what you call "electropower".

The battery provides a non-electrostatic force to make the positive and negative electrodes of the battery gather positive and negative charges separately, even if a voltage is formed between the positive and negative electrodes of the battery, if the electrical appliances are connected between the positive and negative electrodes of the battery, there will be current flowing through the electrical appliances.

Proportional relationship. With voltage, it is possible to generate current, but with voltage, it is not necessarily possible to generate current. The voltage must be applied at both ends of the conductor so that an electric current is generated in the conductor, and if it is applied at both ends of something that does not conduct electricity, the voltage is still present but there is no current.

On the other hand, the current always flows from where the voltage is high to where the voltage is low.

The principal unit of voltage in the SI unit system is volts (v), abbreviated as volts, which is represented by the symbol v. 1 volt is equal to 1 joule of work done for every 1 coulomb of charge, i.e. 1v = 1j c. Strong voltages are often measured in kilovolts (kv), and weak voltages can be measured in millivolts (mv) and microvolts (v).

Physical regulations

Physically, the direction of the current is specified, which is the direction of the positive charge's directional motion (i.e., the positive direction of the speed of the positive charge's directional motion or the opposite of the speed of the negative charge's directional motion).

The direction of current motion is opposite to the direction of electron motion. Charge refers to the free charge, which is free electrons in metal conductors and positive and negative ions in aqueous solutions of acids, bases, salts.

The above content reference: Encyclopedia - Voltage.

The voltage does not change with the current, only the current changes with the voltage. Voltage is the "driving force" that produces the current, and it can be proved that the current is related to the voltage by experimenting and using the control variable method to control all other factors that may affect the magnitude of the current.

When the resistance is constant, the current in the conductor is proportional to the voltage across the conductor. When the voltage is constant, the current passing through the conductor is inversely proportional to the resistance of the conductor.

If there are other electrical appliances in the same circuit in addition to this resistor, then it will have an impact on the voltage. However, its effect only affects the distribution of voltage across the appliance. That is, the greater the resistance, the greater the power supply voltage allocated by the resistor itself, and the smaller the voltage at both ends of other electrical appliances.

The formula for current and voltage is: i=u r, u=ir.

Ohm's law: U=IR (i is the current, r is the resistance) but this formula only applies to purely resistive circuits.

The relationship between the series voltage, the total voltage is equal to the sum of the partial voltage, the characteristics of the parallel voltage of U=U1+U2, the branch voltage is equal to the power supply voltage, U=U1=U2.

The voltage law of the series circuit: the total voltage at both ends of the series circuit is equal to the sum of the voltages at the two ends of the circuit of each part.

Formula: u=u1+u2.

Parallel circuit voltage law: The voltage at both ends of each branch of the parallel circuit is equal and equal to the power supply voltage.

Formula: u=u1+u2.

The current is generated by the voltage, so there must be a voltage if there is an electric current.

On the contrary, there is voltage and there is not necessarily current, for example, if a battery is placed on the ground, there is voltage in the positive and negative poles of the battery, but there is no current; Another example is that a conductor rod cuts a magnetic inductance line without a loop, which will generate an induced voltage but no induced current.

Therefore, we have introduced the concept of resistance, and we also have the determinant formula i=u r for current, and the current is determined by both voltage and resistance, and we can't just look at one. The higher the voltage, the greater the current, and the greater the resistance, the smaller the current.

In the above two examples, because the voltage exists, but the resistance is too large (the positive and negative electrodes are connected to a section of air, and the resistance is very large), so the current generated is considered to be negligible.

As for the absence of voltage, it is okay if the object is not electrified. But there must be no current.

Extended Materials. In fact, the understanding of electric current can be compared to the flow of water, and the general voltage is the potential difference, which can be compared with the height difference.

From the mountain peak to the valley, there is a height difference between the two places, and this height difference is also the voltage; Water flows downward by gravity, which is equivalent to electrons flowing under the action of electrostatic force, which is analogous to an electric current; The passage of water between the mountain peaks and the valley also has a hindrance effect on the water, which is called resistance. For example, building a dam halfway up the mountain will stop the flow of water, which is a big resistance.

It is also easy to conclude here that in order for water to exist, there must be a height difference before the water will flow low; But there is only a difference in height, and the water does not necessarily flow, because a dam may have been built.

Therefore, there must be a voltage where there is a current, and there is a voltage but not necessarily a current.

A battery, in physics, is a device that uses non-electrostatic force to do work to convert other energy into electrical energy. Why is it a non-electrostatic force, because only the electrostatic force exists naturally in nature, and the work done by the electrostatic force will convert the electric potential energy into kinetic energy, which will only consume electrical energy. In fact, the battery is also a water pump, contrary to the laws of nature, the water must be pumped from low to high to produce a height difference, in order to have a steady flow of water.

Without a pump, the water at the top of the mountain will run out sooner or later.

100w12v bulbs are generally DC bulbs, while 110v or 220v are usually AC power, 12V bulbs can not be used on 110V or 220V AC power, this is due to the process of filament making, even if it is not AC power, if 12V bulbs are used in 36V power supply, they will be burned out!

p=ui, in the case of p is certain, it is obvious that the voltage u increases, and the current i decreases; What you probably don't understand is that when the voltage increases, the resistance does not change, and the current should increase, right? Note that the premise here is that the power is the same, it is better to say that you use the same bulb to connect two batteries with the same output power but different output voltages, then the battery with the higher voltage will output less current.

However, in the case of a change in output power, it can be calculated with p=u*u r, and it can be seen that the output voltage increases and the power obviously increases (the resistance is constant), and the current also increases. The difference here from the previous one is that the power has changed.

I don't know if you can understand that?

The current can be compared to the image of the water flow, the electric potential is like the height, the current flows from the high potential to the low potential, just like the water flows from the high to the low, the water with the same height will not flow, as if the electric potential is the same will not have the current, the voltage is the potential difference, the potential difference is zero is the voltage is zero, the role of the power supply is like a water pump, the water pump pumps the water from the low to the high place, and the power supply sends the carriers from the low potential to the high potential.

To sum up, with the same height and the same water pressure, there will be no water flow; Without a pump, all the water would go to the lowest point and there would be no flow. If you compare it to electricity, you should be able to understand it.

It should be said that the relationship between current and voltage. Because voltage is an independent variable and current is a strain variable.

Generally speaking, for a circuit, the higher the voltage, the greater the current. For linear materials such as metallic conductors, the current and voltage are proportional and can be described by Ohm's law, i.e., i=u r. Note that not all materials are suitable for Ohm's law.

The output of electrical energy is a fixed value, and power.

When the voltage rises and the power does not change, the current must decrease by p=ui

Voltage boost is mainly used in power transmission and distribution, reducing the current heat loss is because Q=i RT, in the process of power transmission, due to the resistance of the wire, the smaller the current, the lower the actual loss, then the electrical loss can be reduced.

Voltage is the difference in potential.

If it is an equipotential surface, there is no voltage.

To put it simply, there is no voltage where the electric potential is equal.

If you find it difficult to understand, you can analogize the gravitational potential energy, which is relative to the gravitational potential energy at a height such as the zero potential energy surface).

No, with 110v

220V will burn the bulb out.

There is no such thing as a voltage increase and a certain amount of power. When the voltage increases, the power must generally increase. It is p that is determined by the ui, not p that can determine the ui.

If you don't understand, you can ask me.

Friends understand the opposite, as for high voltage and low current.

Or the need for low voltage and high current is the requirement of different loads for power supply, and the load determines the power supply"Ohm's law is that voltage is proportional to electric current"It doesn't matter at all, for example, a motor of the same power is used in the mains or a car (starting) must be two design schemes, that is, the mains must be"High voltage and low current.

The one used in the car (such as 12V) must be low voltage and high current.

For example, there are more high voltages and low currents.

The voltage of various electron beam equipment is 10,000 volts, and the current is milliampere.

Low-voltage and high-current equipment, electrolysis equipment, the actual voltage of several volts or tens of volts, and the current is thousands or tens of thousands.

Their relationship is expressed by the formula: u=i*r;

The current is proportional to the magnitude of the voltage and inversely proportional to the magnitude of the resistance.

When the voltage is constant, the resistance increases, the current decreases, and the resistance decreases, and the current increases.

When the resistance is constant, the voltage increases, the current increases, and the voltage decreases, and the current decreases;

When the current is certain to return, the voltage, segment and resistance are also determined.

Relationship between current and voltage: i=u r.

According to Ohm's law: the relationship between current and voltage: i = u r. where the unit of current i is ampere, the unit of voltage u is volts, and the unit of resistance r is ohm.

Use the combination of numbers and shapes to analyze the relationship between current, voltage and resistance

1. In physics, images are often used to represent the change of one physical quantity with the width of another, which can intuitively and vividly represent the change law of physical quantity. In the experiment of the relationship between current and voltage and resistance, the image method is applied; The data obtained from the experiment are traced, and the image of the current changing with voltage when the resistance is unchanged and the image of the current skin slowly changing with the resistance (or the reciprocal of the resistance) when the voltage is unchanged are drawn, and the relationship between the current and the voltage and resistance can be obtained.

2. Because the magnitude of the current is determined by both voltage and resistance, the resistance must be controlled unchanged in the relationship between current and voltage. The image method is used for data processing, and the image drawn is a straight line based on the data, indicating that the current is proportional to the voltage under the condition that the resistance is constant. <>