Why can a rheostat change the voltage, and can a sliding rheostat change the voltage?

In series and parallel circuits, the resistance of the sliding rheostat changes. According to the principle of voltage division in series and shunt in parallel:

In series circuits, the ratio of voltage is equal to the ratio of resistance. (because the currents are equal everywhere).

In parallel circuits, the ratio of current is equal to the inverse ratio of resistance. (because the voltages at both ends are equal).

Therefore, when the resistance of the sliding rheostat (connected to the circuit) changes, the voltage or current changes. In the experiment, the resistance of the fixed-value resistor is certain (the characteristic of the fixed-value resistance), and what changes is the voltage or current at both ends of it.

The change in the resistance of the sliding rheostat will affect the voltage and current distribution of the entire circuit, but it is conditional.

For example, in a series circuit, the resistance of a sliding rheostat becomes larger, resulting in a larger total resistance, and a smaller total current because the supply voltage does not change. Because the voltage at both ends of the sliding rheostat and the fixed-value resistor add up to the voltage of the power supply, and the ratio of the voltage at each end of them is proportional to the resistance, the voltage at both ends of the sliding rheostat becomes larger, and the voltage at both ends of the fixed-value resistor becomes smaller.

In the case of parallel circuits, the resistance of the sliding rheostat becomes larger, which increases the total resistance, and the trunk current becomes smaller because the supply voltage does not change. In the branch of a sliding rheostat, the current becomes smaller because the voltage does not change (it is still the supply voltage) and the resistance increases.

Resistance is related to the composition of the material. Gold and silver have the smallest resistivity and can be used to conduct electricity, but considering economic factors, the resistivity row of copper is slightly larger than them, but most of the wires are copper wires. This is a property of the object.

There are also some insulators with great resistance, and some semiconductors and superconductors, in fact, these are related to the properties of matter"Fixed-value resistance"Meaning: the resistance does not change.

If it is connected in parallel with a conductor, it only plays a shunt role and does not change the voltage.

In the case of series connection, the voltage division is played because both the conductor and the rheostat have different voltages.

It's hard to explain in words alone, so you might as well ask the teacher.

Sliding rheostats.

It is a circuit element that can be used to control the circuit by changing its own resistance. In circuit analysis, a sliding rheostat can be used either as a fixed-value resistor or as a variable-value resistor. The composition of the sliding rheostat generally includes five parts: binding post, sliding vane, resistance wire, metal rod and porcelain cylinder.

The resistance wire of the sliding rheostat is wound on an insulating porcelain cylinder, and the resistance wire is coated with an insulating varnish.

There is a sliding rheostat and a fixed value resistor in a circuit, because the resistance of the fixed value resistor is unchanged, we move the sliding blade of the rheostat to make the resistance of the rheostat smaller, and the current in the circuit will become larger, and the voltage at both ends of the fixed value resistor will be greater from i=u r.

As for why this resistance does not change? Isn't the resistance of a sliding rheostat smaller? This is because we measure the voltage at both ends of the fixed value resistor, and the resistance of the fixed value resistance does not change, and R represents the resistance of the fixed value resistance, which has nothing to do with the resistance of the whole circuit or the sliding rheostat.

The principle of resistor series voltage division.

A sliding rheostat can change the voltage of the consumables at both ends of the circuit in series, but it cannot change the supply voltage.

For example, a sliding rheostat is connected in series with a constant-value resistor across a power supply with a constant voltage. When the sliding rheostat slide moves, the resistance value of its own access circuit changes, resulting in a change in the total resistance of the circuit, which can be known by Ohm's law, the total voltage does not change, and the total resistance changes, which will inevitably lead to a change in the total current in the circuit.

Then apply Ohm's law to the fixed-value resistance: the resistance of the fixed-value resistance does not change, and the current passing through it changes, so that the voltage at both ends of the fixed-value resistance must change. In this way, the sliding rheostat achieves the effect of changing the voltage at both ends of the fixed value resistor.

The sliding rheostat is a circuit element, which can change its own resistance and play the role of controlling the circuit from Lu Shijian. In circuit analysis, a slide talk dynamic rheostat can be used as both a fixed and variable value resistor.

The relationship between resistance and voltage: Euclidean's law.

The resistance of a fixed-value resistor cannot be changed. The characteristics of the resistive element itself are only related to the resistive element itself.

Resistors can bear voltage, but they cannot generate voltage. The voltage is generated by the power supply. A closed circuit consisting of a power supply, a resistive element, and a wire generates an electric current.

When an electric current is passed through a resistive element, the resistive element has a voltage. It can also be said that the voltage of the resistance is determined by the current because the current flows through the resistor, so the voltage of a fixed value resistor is determined by the current.

Like you said, sliding variable resistance crying, changing the voltage by changing the resistance value, this sentence is true. When the sliding rheostat cry is connected in series with the power supply, the resistance value is changed, and the voltage is also unchanged. u=ir。

As can be seen from this formula, when the resistance value changes, the current also changes, and the change in voltage cannot be determined. And what you said, when the current changes, the voltage changes, the premise of this sentence is that the resistance does not change.

I don't know if you understand what I'm saying. Voltage and resistance are two different concepts. Two natures.

Two physical quantities. There is a relationship between these two physical quantities, but it is not a decisive relationship. The determinant of any physical quantity is its own property.

They cannot be misled by the formula connections between them.

Voltage = Resistance * Current.

Current = Voltage Resistance.

Resistance = voltage and current.

Note that a common mistake made in this formula is the phrase "resistance follows conduction."

The voltage of the two segments of the body is directly proportional to the current", this statement is wrong, the resistance is the inherent property of the conductor itself, only with the material, temperature (in middle school.

Exposure to these) is not related to voltage and current, and this question is often selected.

Resistance is a property of a substance, and the resistance of different materials is not the same, and it has nothing to do with voltage.

When the current is constant, the resistance becomes larger, and the voltage becomes larger. The resistance of a conductor to an electric current is called the resistance of the conductor. Voltage, also known as potential difference or potential difference, is a physical quantity that measures the difference in energy between a unit charge in an electrostatic field and the difference in potential.

Resistance resistance (usually denoted by "r") is a physical quantity that represents the magnitude of a conductor's resistance to the current at the side. The greater the resistance of a conductor, the greater the resistance of the conductor to the current. The resistance of conductors with different nuclei is generally different, and resistance is a property of the conductor itself.

The resistance of a conductor is usually represented by the letter r, and the unit of resistance is ohm, referred to as ohm, and the symbol is .

The magnitude of the voltage is equal to the work done by the unit positive charge to move from point A to point B due to the action of the electric field force, and the direction of the voltage is specified as the direction from the high potential to the low potential. The SI unit system of voltage is volts (V, referred to as volts), and the commonly used units are millivolts (mV), microvolts (V), kilovolts (kv), etc. This concept is similar to the water pressure caused by the water level.

It should be pointed out that the term "voltage" is generally only used in electrical circuits, while "potential difference" and "potential difference" are generally applied to all electrical phenomena.