Is there no resistance without current, and there is no voltage without resistance

The dampening effect of a conductor on an electric current is called resistance, and it is determined by the nature of the conductor material and has nothing to do with the current flowing through it. Resistance is not generated with the generation of current, nor does it disappear with the disappearance of current, resistance reflects the conductive characteristics of conductive objects, that is, the problem of conductivity. To give a popular example (perhaps not very appropriate), resistance is like a dam, and an electric current is like a flow of water, when there is a flow of water through the dam, the dam will have a certain obstruction effect on the flow of water, but when there is no flow, the dam still exists, but its obstruction effect is not visible because there is no flow.

This statement should not be true.

Resistance is a property of the substance itself, and the equation that determines the magnitude of the resistance is:

r＝p*l/s

where p is the resistivity, which is related to the constituent elements of the substance (I can't type that Greek word, replace it with p), l is the length, and s is the cross-section.

The magnitude of r has nothing to do with the current.

Upstairs should be clear.

You must have encountered a situation where the wireframe enters the magnetic field regardless of the resistance.

Since it is a superconductor, it is absolutely impossible to have a stable electromotive force, otherwise the current tends to infinity due to Ohm's law. Therefore, the self-induced electromotive force generated by the coil is equal to the induced electromotive force given by the external magnetic field.

But there is an electric current in the wireframe, because the superconductor does not hinder the current, and the generated current can be retained forever, so there is an induced current, which is subject to ampere force.

So how do you calculate the induced current?

In fact, consider a very short time t, during which the current has an increment of i (due to the self-induced electromotive force), e from l* i t e inductance, i.e. l i e induction t

Sum the two sides of the above equation, l*i e sense t

If it is a kinetic induction, E is blvi* t=bl x, and the sum is blx

Special statement: The above calculations are part of the competition, if you only need to take the college entrance examination, you only need to master the previous qualitative analysis.

Upstairs upstairs and upstairs upstairs upstairs are right.

Resistance is the property of the object itself.

It has nothing to do with whether there is an electric current or not.

Upstairs it's already clear.

It's not that there is no voltage without resistance, resistance can indeed cause a decrease in voltage, but it is not necessary to have resistance for voltage to appear. Voltage refers to the potential difference produced by the force of an electric field in a circuit and is the form of energy that a charge has as it flows through a circuit. If the circuit does not have any resistance, the current will flow without restriction, which is known as a short circuit.

In this case, the voltage does not decrease, but rather causes a high loss of current and energy. Therefore, according to Ohm's law, the voltage can only produce the corresponding current when there is a resistance ruler in the circuit, and the relationship between voltage and current is described by the resistance value of the resistor. However, it is important to note that resistance is not the only factor that affects voltage, for example, capacitors, inductors, and other components in a circuit can also cause changes in voltage.

Superconducting materials can suddenly lose their resistance at a certain temperature (zero resistance effect).

When a superconducting material enters a superconducting state, there is a magnetic flux effect, known as the Meissner effect;

The Meissner effect is used to create superconducting trains and superconducting ships, which will greatly increase their speed and quietness and effectively reduce mechanical wear and tear as these vehicles will operate in a suspended and frictionless state. Wear-free bearings can be manufactured using superconducting levitation, increasing the bearing speed to more than 100,000 revolutions per minute. Superconducting trains have been successfully tested for manned feasibility in the 70s, and since 1987, Japan has begun trial operation, but failures often occur, which may be caused by bumps caused by high-speed driving.

The superconducting ship was launched on January 27, 1992 for sea trials, and has not yet entered the practical stage. There are still certain technical obstacles to the use of superconducting materials to make vehicles, but it is bound to trigger a wave of transportation revolution. The zero-resistance properties of superconducting materials can be used to transmit electricity and make large magnets.

The use of superconductors can minimize the losses of ultra-high voltage transmission, but the use of superconductors at high critical temperatures has not yet reached the practical stage, which limits the adoption of superconducting transmission. With the development of technology and the continuous emergence of new superconducting materials, the hope of superconducting power transmission will be realized in the near future. ”

So far, there are two main types of high-temperature superconducting materials: copper oxide high-temperature superconductivity and iron-based high-temperature superconductivity. So far, 4 Nobel Prizes have been won in the field of superconductivity, and there will be at least one room temperature superconducting material in the future; At present, the highest superconducting temperature at high pressure is 167K

There is no resistance in the circuit, which means that the circuit does not consume electrical energy due to heat generation, however.

There can also be capacitors, inductors in the circuit.

Capacitor: A component that stores electrical energy, which is connected to a circuit, and the power supply can charge the capacitor and store the electrical energy.

In capacitors, the higher the capacitance value, the more electrical energy is stored. It has the effect of resisting direct current (electricity) and passing through AC.

Inductor: A component that stores electrical energy, and the energized inductor can convert the electrical energy into magnetic field energy and do work externally, such as an electric motor.

Therefore, it is not terrible that there is no resistance in the circuit, except for the use of electrical appliances that generate heat, and the rest of the circuit is resistance.

The smaller, the less electrical energy is wasted in the circuit, and the higher the utilization rate of electrical energy. It's a good thing, rest assured, it won't burn out the circuit!

Theoretically, the resistance becomes zero at absolute zero, and the incoming circuit can be considered infinite.

But this is only theoretical, in practice absolute zero is unattainable, and zero resistance is even more unattainable.

A denominator equal to zero is infinity.

These are two different things and cannot be confused???

Summary. <>

Hello, happy to be able to answer your questions!

There is voltage but no current, and at this time, the resistance does not work and becomes a wire. : Yes. The current is the result, there is no current for no reason because it comes from the ratio of voltage to resistance, anything that causes the voltage to be zero or the resistance is very large, will result in the current being zero.

The current is zero, has nothing to do with the wire, and is very inappropriate. If the current is 0, it means that the voltage at both ends of the electrical appliance and the resistor is zero. If my answer is helpful to you, please give a thumbs up (comment in the lower left corner), look forward to your like, your efforts are very important to me, and your support is also the motivation for my progress.

If you feel that my answer is still satisfactory, you can click on my avatar for one-on-one consultation. Finally, I wish you good health and a good mood! <>

There is voltage but no current, and at this time, the resistance does not work and becomes a wire.

Please wait patiently for 3 minutes, we are sorting out, and we will answer you immediately, and please do not end the consultation.

Your question has been received, it will take a little time to type, please wait a moment, please do not end the consultation.

Hello, happy to be able to answer your questions! There is voltage but no current, and at this time, the resistance does not work and becomes a wire. : Yes.

The current is the result, there is no current for no reason because it comes from the ratio of voltage to resistance, anything that causes the voltage to be zero or the resistance is very large, will result in the current being zero. The current is zero, has nothing to do with the wire, and is very inappropriate. If the current is 0, it means that the voltage at both ends of the electrical appliance and the resistor is zero.

If my answer is helpful to you, please give a thumbs up (comment in the lower left corner), look forward to your like, your efforts are very important to me, and your support is also the motivation for my progress. If you feel that my answer is still satisfactory, you can click on my avatar for one-on-one consultation. Finally, I wish you good health and a good mood!

Voltage is responsible for the formation of electric current. So where there is current, there must be voltage. If there is voltage, there is not necessarily current, the battery has voltage, but if it is not connected in the circuit, there is no path, there is no current.

Voltage is what causes an electric current to form in a circuit. In order for there to be current in the circuit, two conditions must be met: there is voltage at both ends of the circuit; The circuit should be closed.

The actual direction of the voltage is the direction in which the positive charge is subjected to the force in the electric field. When calculating complex circuits, it is often difficult to determine the actual direction of the voltage, so it is necessary to set the reference direction of the voltage first. In principle, the reference direction of the voltage can be arbitrarily selected, but if the current reference direction is known, it is better to choose the voltage reference direction that is consistent with the current, which is called the correlated reference direction.

When the actual direction of the voltage coincides with the reference direction, the voltage is positive; Otherwise, it is negative.

No. It's like charging a mobile phone, where does the charging come from if you don't plug it in, the principle is the same.

In the absence of resistance and voltage, it is possible to generate current, but this kind of current generally exists in nature and is a natural phenomenon, and artificial electricity must have resistance and voltage!

If the circuit is closed and there is no resistance, the current will be very large, and how large it will be, depending on the supply voltage and its internal resistance.

No current can be generated. If there is no resistance but there is voltage, it can still form a potential difference, and the electrons will still move directionally to produce current, but the current size is unmeasurable, but without resistance and voltage, it must not produce current.

Not inversely proportional.

The resistance is determined by the nature of the device itself, and has nothing to do with the magnitude of the voltage and current. For example, even if there is no voltage or current, the resistance of the device itself is still present. Formulas in physics cannot be simply analyzed as mathematical expressions, although sometimes two commons are the same from a mathematical point of view, but the physical meaning may not be the same.

In physics, there are also two formulas to be aware of, one is definitive and the other is deterministic. For example, r=u i is the definition of resistance, r=ps l is the calculation formula of resistance (p is resistivity), from the calculation formula of resistance, it can be seen that the size of the resistance is only related to the resistivity of the resistance, the length of the resistance and the cross-sectional area of the resistance, and whether there is an external voltage. When you learn about electromagnetism in the future, you will have a lot of similar questions.

The series voltage divider means that the greater the resistance in the circuit, the greater the voltage divided. In this series of resistors, whoever has the greater resistance will receive more voltage. Indeed, because the current flowing through the resistor string is equal, whoever has the greater resistance will receive the higher voltage.

What you are talking about, increase the resistance of the sliding rheostat, when the voltage source: the total voltage does not change, the total resistance increases, so the current in the circuit becomes smaller, so the voltage distributed to other resistors (the resistance value does not change) becomes smaller, and the voltage distributed to the sliding rheostat becomes larger. When the current is sourced:

The current does not change, so the voltage on the other resistor heads does not change. The voltage distributed by the sliding rheostat increases due to its increased resistance.

u=ir

The formula is a relation to the condition that the resistance can be changed, and when on a fixed conductor, the resistance is an intrinsic property of itself and does not change. It has nothing to do with voltage.

Solution: If there is no resistor, it will be like this

A very small voltage can produce an infinite amount of current.

It's like superconductivity.

Nothing like this will happen.

At least not yet.

Joule's law, the same resistance is the same electric current.

It can be explained by Kirchhoff's law of currents:

Kirchhoff's current law (kcl).

The algebraic sum of all currents flowing out of any node in a lumped parameter circuit at any moment is constant zero;

Electricity is like water.

Compare an electric current to the flow of water.

The line is likened to a river.

Then the flow of water through any place is equal! ~