Elementary 2 electrical problems about the relationship between current, voltage and resistance .

The battery has internal resistance, which is equivalent to a small resistance inside the battery and the circuit in series, when the external resistance value is increased, the external partial voltage becomes larger, and the voltmeter measures the external voltage, so the value will become larger, dare to raise their own doubts, and it is so sharp, you are very promising, hehe.

It must be that there are not only small bulbs in the circuit, but also sliding rheostats.

The total voltage is certain, but if there are two electrical appliances, then the total voltage has to be divided between these two electrical appliances, whose resistance is larger, who has more voltage, so you adjust its resistance to increase, and indeed the current becomes smaller, but because its resistance becomes larger, the voltage of the division is more, according to the principle of series voltage division.

The power supply is a battery, and the battery has an internal resistance r, so that the circuit can be seen as a pure power supply e connecting two series resistors r and r (small bulb resistance).

If r increases, then the amount of charge that e distributes to each resistor decreases, and the current i decreases.

When the current decreases, the voltage on R decreases, so the voltage increases because the voltage on the small bulb U=E-IR.

The key here is that the power supply used in the experiment is not a pure power supply, it has internal resistance.

Probably considering the internal resistance r of the power supply.

It is equivalent to a fixed-value resistor.

The voltage u shared by the internal resistance r of the power supply decreases as the current decreases.

The power supply voltage is certain.

Therefore, the voltage shared by the small bulb increases.

The mathematical relationship between voltage and resistance is: r=u i, i.e., resistance = voltage and current. But note that in physics, resistance indicates the magnitude of a conductor's resistance to an electric current.

In the case of a certain temperature, the magnitude of the conductor resistance is determined by the material, length, and cross-sectional area of the conductor itself. It has nothing to do with whether the circuit is connected, the applied voltage, and the size of the current through it.

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 changing the magnitude of this resistance, the current is generated. The size 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. 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 kind of situation, the electrical appliance can be connected in series with a suitable resistance value, so that it can share a part of the voltage, and the electrical appliance can work under the fixed voltage. We call such resistors voltage-dividing resistors.

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

Ohm discovered the proportional relationship between current and voltage in resistors, known as Ohm's law: in the same circuit, the current in a conductor is directly proportional to the voltage at both ends of 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.

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.

Omding: i=u r resistance can be understood as the rubber blocking the current from passing, so the greater the resistance, the greater the physical force of the resistor, the smaller the current. Therefore, when the voltage is constant, the current is inversely proportional to the resistance.

When the voltage is constant. It is not because the current changes, and the resistance of the resistance changes inversely with the change of current. Rather, it is to artificially change the resistance to a different resistance, and the current changes inversely with the resistance, in other words; The current does not control the change in the resistance value.

Resistors can control the change of current.

1.Material: Conductors of different materials generally have different resistances.

2.Length: Conductors of the same material and thickness, the longer the length, the greater the resistance; The shorter the length, the lower the resistance.

3.Cross-sectional area: For conductors of the same material and the same length, the larger the cross-sectional area, the smaller the resistance. The smaller the cross-sectional area, the greater the resistance.

4.Temperature: All other factors are equal, in general, the resistance becomes larger when the temperature rises and decreases when the temperature decreases.

Scientifically, the amount of electricity passing through any cross-section of a conductor per unit of time is called current intensity, referred to as current. The French physicist and chemist André Marie Ampère made outstanding achievements in the field of electromagnetism, as well as in the study of allegiology and physics. The SI unit of electric current, the ampere, is named after its surname, abbreviated as "ampere", and the symbol "a", which also refers to the directional movement of electric charge in a conductor.

Nature has many kinds of carriers that carry electric charges, for example, electrons that can be moved in a conductor, ions in an electrolyte, electrons and ions in a plasma, quarks in hadrons. The movement of these carriers forms an electric current.

Physics questions for the ninth grade: resistance = voltage and current, electric power = voltage and current, and the same fugue is the operation between voltage and current, why is resistance and voltage and current not clear, and electrical power is related to voltage and current?

Resistance = voltage and current, so resistance is related to voltage and current.

The voltage is certain. Resistance is inversely proportional to current u=IR

Resistance is certain. The voltage is proportional to the current r=u i

The current is certain. The voltage is directly proportional to the resistance. i=u/r

Resistance is a property of the conductor itself, which is only related to the material, length, cross-sectional area and temperature of the conductor, and has nothing to do with voltage and current, but can be calculated by the ratio of voltage to current.

At a certain voltage, the current passing through the conductor is inversely proportional to the resistance of the conductor.

At a constant resistance, the current passing through the conductor is proportional to the voltage across the conductor.

i=u ri is the current.

u is the voltage. r is the resistance.

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

Knowing the current and voltage, find the resistance, then: r=u i

Know the current resistance, find the voltage, then: U=IR

Knowing the resistive voltage and finding the current, then: i=u r

This is Ohm's law.

Voltage U = current i times resistance r or current i = voltage u divided by resistance r

The basic Ohm's law, i*r=u

As can be seen from the title, the value of the rheostat does not change due to the access resistance.

Therefore, its role in the circuit is equivalent to a fixed-value resistor.

The question becomes:

When a fixed-value resistor is connected in series with a 5 ohm resistor on a circuit, the voltage across the 5 ohm resistor is 3 volts.

With a certain value of resistance, when the 10 ohm resistor string is on the same power supply, how much should the voltage at both ends of the 10 ohm resistor be?

Series resistance when connected to 5 ohm resistor: r string 1 r+5;

Series resistance when connected to 10 ohm resistor: r string 2 r + 10Although 10 is twice as much as 5. However, r-string 2 is smaller by 2 (r+5).

So, the relationship between the two series currents:

i2 Therefore, the voltage at both ends of the fixed value resistor u2 is so, the voltage at both ends of the 10 ohm resistor is greater than 3 volts.

However, it cannot be equal to 6 volts, but less than 6 volts.

1.When a voltage of 2 volts is applied at both ends of a conductor, the current intensity through it is ampere, and the resistance of this conductor is (5); If no voltage is applied at both ends, the current intensity through it is (0) and the resistance of this conductor is (5).

2.In the circuit shown in the figure, the resistance of r is 2 ohms, the voltage at both ends of the bulb is 3 volts, and the power supply voltage is 4 volts, then the voltage at both ends of r is (1) volts, and the resistance of the bulb is (6) ohms.

3.The resistance value of the resistor r is determined by the voltmeter and ammeter, and the equipment used is: battery pack, switch, ammeter, sliding rheostat, wire and resistance r to be measured

2) The function of using a sliding rheostat in the circuit is to protect the circuit, change the voltage at both ends of the resistor, and take multiple measurements to average and reduce the error).

3.A 36-volt power supply, a switch and some identical small bulbs, let each bulb glow normally, its current is 2 amps, the resistance is 6 ohms, if you want to use these materials for lighting, you can connect (3) bulbs (series) and connect them to the circuit to achieve the purpose of normal light. The basis for this is (series partial pressure).

2. What about the figure? 3. Protect the circuit, regulate the voltage and current.

Series connection: The current of each electrical appliance in the series circuit is equal, and the sum of the voltages is the total voltage.

The specific function of a sliding rheostat is to reduce the error on average, but what is an example? What is it, can you cite an easy-to-understand one.