When the current is constant, the relationship between voltage and resistance

1.When studying the relationship between current and voltage, a positive ratio is determined by the readings of two tables.

Linear functional relations, this is Ohm's law.

u=r*i, because the voltage and current on r are always measured, and the only way to reflect this function is to observe the change of voltage with current. Change the sliding rheostat.

The total resistance of the circuit can be changed so that the current can be changed, so that the different voltages at both ends of the fixed resistance can be observed. Since it is always the voltage and current at the same fixed value resistor, it is possible to find out the proportional relationship between them.

If the fixed value resistor of different specifications is changed, the total resistance of the whole circuit will change, the current will change, and the voltage will change. However, it should be noted that because the fixed value resistor is replaced every time, its voltage and current ratio is different each time, so there is no way to find out the relationship between voltage, current, and resistance. In other words, the purpose of studying the voltage-current relationship of a certain resistor cannot be achieved.

To put it simply: changing a different fixed value resistor can change the voltage at both ends of "it", but this "it" is no longer the original "it".

2.When studying the relationship between current and resistance, why should the sliding rheostat not change the voltage at both ends of the fixed value resistor, and does the replacement of the fixed value resistor not affect the voltage at both ends?

When you ask, my understanding is that the sliding rheostat is always in a special state at this time, that is, the contact is at the far left, which means that the sliding rheostat is not connected or short-circuited, and at this time, the two ends of the fixed value resistor are always the power supply voltage (the power supply is set to ideal, otherwise there will be problems). At this time, no matter how large the fixed resistance is, its voltage is the supply voltage, that is, it remains the same. If you change the fixed resistance, the current will change accordingly.

The relationship between the two also satisfies Ohm's law. If the contact of the sliding rheostat is not at the far left, then it has its own resistance in the circuit, and changing the fixed resistance will affect the total resistance of the circuit, so that the current changes, and then the voltage at both ends of the sliding rheostat and the fixed value resistor change. At this point, the purpose of the measurement is not obvious.

Only the current must not be able to determine the relationship between voltage and resistance, it should be determined in the case of the specified electric power, the electric power refers to the work done per unit time, the symbol is p, and the formula is p w t (power work time).

p i 2 * r (the square of the current i multiplied by the resistance r) = u 2 r (the square of the voltage u divided by the resistance).

It cannot be said: the current is certain, and the voltage is proportional to the resistance.

It can only be said: the resistance is certain, and the voltage is proportional to the point flow.

This is Ohm's law, which is the defining formula of resistance, not the deterministic formula.

The current is constant, and the voltage and resistance are constant

Hello, when the resistance is constant, the current and the voltage are proportional, the larger the corresponding voltage, the greater the amount of current, but the resistance is a fixed value does not change, but in reality, because the current is larger, what about the future? What about the heat generated by conductors? Therefore, when we use Ohm's law to plot the volt-ampere characteristics of the conductor, we will find that in fact, the voltage value exceeds a certain value, and the volt-ampere characteristic curve will bend in the future, but it is not always an inclined straight line.

The role of resistance in a circuit.

1.The current-limiting effect of resistors in circuits. In order to ensure the normal operation of the electrical appliance, a variable resistor can usually be connected in series in the circuit in order to ensure the normal operation of the electrical appliance.

When the magnitude of this resistance is changed, the magnitude of the current also changes. We call this resistor, which can limit the amount of current, a current-limiting resistor.

2.The shunt effect of resistors in electrical circuits. When several electrical appliances with different rated currents need to be connected at the same time on the main circuit of the circuit, a resistor can be connected in parallel at both ends of the electrical appliances with smaller rated current, and the function of this resistor is to "shunt".

3.The voltage-dividing role of resistance in a circuit. Generally, electrical appliances are marked with rated voltage values, if the power supply is higher than the rated voltage of the electrical appliances, the electrical appliances should not be directly connected to the power supply.

In this case, the electrical appliance can be connected in series with a resistor of a suitable resistance value, so that it can share a part of the voltage, and the electrical appliance can work at the rated voltage. We call such resistors voltage-dividing resistors.

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

When the resistance is constant, the higher the voltage, the greater the current, the voltage is proportional to the current, when the current is constant, the voltage is inversely proportional to the resistance, the resistance is equal to the voltage divided by the current, which is Ohm's law.

The relationship between current and voltage and resistance is noted below

When the voltage is constant, the current is inversely proportional to the resistance; When the resistance is constant, the current is proportional to the voltage, which is expressed by the formula: i=u r. Ohm discovered the proportional relationship between current and voltage in resistance, the famous Ohm's law:

In the same circuit, the current in the conductor is directly proportional to the voltage across the conductor and inversely proportional to the resistance of the conductor.

Ohm's Law. Ohm's law describes the physical relationship between current and voltage in a conductor, i.e., the current passing through the conductor is proportional to the voltage at both ends of the conductor and inversely proportional to the electrical composition of the conductor, which can be written as i=u r in mathematical expression.

When applying Ohm's law, it must be noted that the so-called resistance is a physical quantity that has nothing to do with voltage and current, and it is related to the material, geometry, temperature, pressure, light and other considerable environmental parameters, that is, whether there is voltage or current, the resistance is objective, which is particularly easy to cause misunderstanding when applying the deformation formula of Ohm's law r=u i.

In addition, u, i, and r must be examined under the same conditions, for example, when talking about the voltage on the conductor, it must be understood that it is for the voltage between which position of the conductor and which position.

The resistance must also be between these two positions, and the current must be the current flowing in and out of this conductor, otherwise it is easy to make mistakes, especially when applying Ohm's law for part of the circuit.

The other is the temporal characteristic, which means that the application of voltage, current and resistance must be simultaneous, that is, the so-called moment. This does not seem to be prone to errors in stable DC circuits, but it is especially important in AC circuits, otherwise it is easy to draw wrong conclusions.

When the current is constant, the voltage is proportional to the resistance, that is, the greater the resistance, the higher the voltage.

This is described by Ohm's law: at a constant temperature, the magnitude of the current passing through a conductor is proportional to the voltage at both ends and inversely proportional to the resistance of the conductor.

The mathematical expression for Ohm's law is: V=IR, where V is the voltage, I is the current, and R is the resistance. This equation shows that when the resistance increases, the voltage also increases, while the current remains the same.

Knowledge Expansion and Frank Expansion].

1.Potential difference (voltage): The potential difference refers to the energy possessed by a unit charge in an electric field. In a circuit, the potential difference can be used to describe the voltage of the power supply and the voltage difference between the individual components.

2.Current direction: In a circuit, the direction of current is usually from the positive to the negative. However, in some cases, the direction of the current may be reversed, such as in an AC circuit, the direction of the current is constantly changing.

3.Resistivity: Resistivity is a material's ability to resist electric current. Different materials have different resistivity and can be used to make resistors or wires with different resistance values.

4.Thermal effect: In a circuit, heat is generated when an electric current is passed through a conductor. This phenomenon is called the thermal effect. Thermal effects can cause changes in the value of resistance in circuits and can also be used to make devices such as electric heaters.

5.Inductively Coupled Closed Lift: In some circuits, there may be inductive coupling between two inductors. This coupling causes changes in the current and voltage in the circuit, which can be used to make devices such as car wide filters. <>

The relationship between current and voltage when the resistance is certain is that the current (i) is equal to the voltage (v) divided by the resistance (r).

1. Basic relationship.

According to Ohm's law, the current (i) is equal to the voltage (v) divided by the resistance (r). The formula is: i = v r.

2. Linear relationship.

Under the premise that Ohm's law is satisfied, there is a linear relationship between current and voltage. If the voltage changes to the sail finger lighting, the current will also change in the same proportion.

3. The influence of resistance.

When the resistance remains constant, the relationship between current and voltage is determined by Ohm's law. A larger resistance causes a smaller current to flow through, and a smaller resistance causes a larger current to flow through. In other words, the greater the resistance, the less current will pass, and the smaller the resistance, the greater the current will pass.

The role of resistors:

1. Limit the current.

Resistors can limit the amount of current in a circuit by blocking the flow of current. By selecting the appropriate resistance value, the current in the circuit can be controlled to meet the operating requirements of the device or component. Current limiting plays an important role in circuits to protect electronic components, prevent fire and electric shock, control power consumption, and stabilize system operation.

2. Adjust the voltage.

The resistor can adjust the voltage in the circuit by selecting different resistance values according to the v = i * r relation in Ohm's law. Through the principle of resistor voltage division, the voltage can be regulated and controlled by reasonably configuring the resistor in the circuit.

3. Protective elements.

In electrical circuits, resistors can be used as protective elements to limit the passage of current. For example, in LED circuits, the use of a current-limiting resistor can prevent excessive current from damaging the LED.

4. a heating element.

The resistor itself produces a certain resistance loss, that is, converts electrical energy into thermal energy. This characteristic is widely used in electric heaters, electric furnaces, and other equipment that needs to generate heat. The functions of heating elements mainly include heating and temperature control, temperature compensation and stabilization, heating test and simulation, resistance adjustment, light source and light-emitting device.

When the voltage is constant, the current is inversely proportional to the resistance; When the resistance is constant, the current is proportional to the voltage, which is expressed by the formula: i=u r. I've compiled relevant knowledge points for you, let's take a look.

When the resistance is constant, the current is proportional to the voltage;

When the voltage is constant, the current is inversely proportional to the resistance;

When the current is constant, the voltage is proportional to the resistance.

A safety voltage is a series of voltages used to supply power from a specific power source to prevent electric shock.

The safety voltage should meet the following three conditions:

1.The nominal voltage does not exceed AC 50V and DC 120V;

2.Powered by a safety isolation transformer;

3.The safety voltage circuit is isolated from the power supply circuit and the ground.

When the electric charge moves in the conductor, it is subject to the collision and friction of other particles such as molecules and atoms, and the result of the collision and friction forms an obstacle to the current of the conductor, and the most obvious feature of this hindrance is that the conductor consumes electrical energy and generates heat (or emits light). This obstructive effect of an object on an electric current is called the resistance of that object.