How is the current calculated when the resistance is zero

1.The ohmic law formula you use i=u r has a scope of application, it is only suitable for ohmic or linear dielectrics that are conductive, and superconductors are non-ohmic dielectrics, so ohmic laws do not apply here.

2.In a more general case, the general company of ohmic electric law is J=y(e)e, j is the current density, y is the electrical conductivity, and e is the electric field, that is, in general, the conductivity itself is also a function of the strength of the electric field, and it is a very complex formula because there are differences in e in different places inside the conductor.

3.In a superconductor, to calculate its current, it cannot be calculated by calculating the voltage and resistance, but needs to be measured directly by an instrument (superconductors have a critical temperature and a critical magnetic field, and of course there is also a critical current, when, b exceeds a certain point, the superconducting state will disappear).

3.In superconductivity, the so-called voltage problem has no real meaning.

Ohm's law is used for pure resistance appliances, that is, electrical appliances that convert electrical energy into heat energy, since they are superconducting, there is no heat energy, and they are not pure resistance appliances, so they cannot be calculated by Ohm's law. Apply an ammeter to measure the current.

It can be solved according to Ohm's law of closed circuits i=e (r+r), where e is the electromotive force, r is the external resistance, and r is the internal resistance.

It is outside Ohm's law.

The superconductor is used as a wire, connected to electrical appliances, and directly connected to the positive and negative poles of the battery will not be short-circuited.

This equal sign is only suitable in a pure resistive circuit, that is, all the work done by the current is used to generate heat, that is, all the current is converted into internal energy. It is not suitable for conversion to other forms of energy, such as electrical appliances such as engines, some of the current is converted, so the motor cannot use this formula. A conductor connected to the power supply will have a current through it, the size of the current depends on the voltage and the size of the conductor resistance, the resistance is constant, the higher the voltage at both ends of the conductor, the greater the current through it, no matter how the voltage changes, the current is proportional to the voltage, that is, the ratio of voltage to the corresponding current is a fixed value, this fixed value is the resistance value of this conductor.

For example, suppose a bulb is connected to a 2V power supply and the current passing through it is connected to a 4V power supply, and the current passing through it is 2, 4, where 10 is a fixed value of the voltage and the corresponding current ratio, so the resistance of the bulb is 10 ohms, with U meter voltage, I meter current, R meter resistance, the three have the relationship of U i=r, and the sub-deformation of the formula can obtain i=u r, which is the expression of Ohm's law. Its physical meaning is: when the resistance of the conductor is constant, the higher the voltage applied to it at both ends, the greater the current passing through it, which is that the current is proportional to the voltage; When the voltage is constant, the greater the resistance of the connected conductor, the smaller the current through the conductor, which is inversely proportional to the resistance.

This formula is a definition, there is voltage, there is current, then I will define voltage divided by current as resistance, and use this resistance to represent the resistance and consumption in the circuit.

So the resistance is equal to u divided by i, that's a definition, and if I'm ox x, I can also define r equals.

It doesn't matter if i divides by u, but because u divided by i is r, according to mathematical knowledge, i is equal to u divided by r

So i equals u divided by r is not some empirical formula or something, but is derived from a person's definition.

In the figure, U is the voltage, I is the current, and R is the resistor.

This is Ohm's law formula i u r.

1. When the voltage U is required, cover U with your hand, and the remaining two quantities I and R are below, which means that I and R are multiplied, so U IR (as shown in the figure below).

<> in junior high school physics, all formulas can be turned into this way to help convert a physical quantity in their hands.

A little more complicated, there is a calorific calculation formula (as shown in the figure below).

You can also use the above method to find the heat q, specific heat capacity c, mass m and temperature change (t-t0) or (t0-t).

The resistance formula (Ohm's law) describes the behavior of an electric current in a resistor, and it is the basic formula used to calculate the current. This formula is based on the relationship between current and voltage observed experimentally.

According to Ohm's law, the current (i) is equal to the voltage (v) divided by the resistance (r), i.e. i = v r. This formula shows that the current passing through a resistor is proportional to the voltage and inversely proportional to the resistance. When the voltage increases, the current will also increase; And when the resistance increases, the current decreases.

This formula is based on understanding electrical resistance. Resistance is the property that hinders the passage of electric current, and it is determined by factors such as the material, shape, and length of the resistor. When an electric current is passed through a resistor, the electrons are subjected to an electric field in the resistor, causing it to collide and be blocked.

Resistance is like an electric current"Obstruction", reducing the flow of current.

Therefore, Ohm's law provides a simple and useful way to calculate current in terms of voltage and resistance. It is one of the most basic formulas in circuit analysis and design, and can be used to calculate currents in a variety of complex circuits. At the same time, Ohm's law can also be used to explain the power consumption and heat generation of resistors, which provides an important basis for circuit design and safety engineering.

I hope mine can help you and have a great day!If you are satisfied with me, you can give me a thumbs up, thank you Ranaiqin.

The resistance formula was obtained through extensive experimental observations. Through observation, it is known that when the resistance is constant, the voltage is positively correlated with the current, and then continuous experiments, measurements, and calculations are made to obtain the formula i=u r. Liang Yin.

Only by knowing the resistance and voltage can the magnitude of the current be derived using the resistance formula.

Add lower than the rated voltage and more voltage U at both ends of the motor, do not let the motor rotate so that the electrical energy is completely converted into heat energy, which can be used to use Ohm's law, and measure the current I and the motor resistance: r = u i.

The power of the motor is the power that converts its electrical energy into mechanical energy, because the motor is special, it converts electrical energy into mechanical energy, and at the same time it has its own resistance, it will generate heat energy, that is to say, electrical energy = mechanical energy + thermal energy.

The presence of voltage and current is not necessarily related to resistance.

According to Ohm's law, i = u r, for a length of conductor, when the voltage across the conductor remains constant, the smaller the resistance, the greater the current.

But when the resistance is 0 (which is difficult to do in reality), i and u are not directly related.

For example, if you only look at a small piece of wire, you can assume that its resistance is 0. The voltage is the potential difference between the two ends, which is also 0. However, the current is the amount of current that passes through the bulb (circuit: power supply, switch, bulb, power supply).

Can you tell us what the situation is?

Experiment 17 ** Relationship between current and voltage and resistance.

According to the direction of the current, you can confirm that the right side is equivalent to the negative pole of the power supply, and set the potential to 0, because the total resistance of each branch is 9, so the current of each branch is, then the resistance voltage on the right side of the upper branch is U1 IR1

The resistor voltage on the right side of the lower branch is U2 IR2

Therefore, the voltage between ab is a negative sign, indicating that the potential at point b is higher than the potential at point a.

If the resistance of both branches is 9 ohms, the current is divided equally.

Take the right end as the reference point and set the voltage to 0

Then the voltage at point A is ohms, and the voltage at point B is 9 ohms.

Then the voltage difference between AB is ohms.

If you want to know the voltage between A B, you need to know how much the voltage between A B is, so you can analyze and know that the voltage in the series circuit is proportional to the resistance, so you only need to know what the voltage of the two circuits A B is.

The calculation is done in reverse.

1 First find the total resistance The resistance of the upper and lower ends is 9, so r=(9*9) (9+9)=

2 The voltage is u= ir=3 terminal A voltage ua= *6= 9

B-terminal voltage ub=

4 The voltage at terminal ab is ua-ub=