In junior high school physics, which experiments used sliding rheostats? What are the roles?

Sliding rheostats are useful in three experiments: "volt-ampere resistance measurement", "verification of Ohm's law", and "measurement of lamp power".

Function: Voltammetry resistor: change the current and voltage values of the resistor to be measured, and take the average value of multiple measurements to reduce the error.

Verify Ohm's law: when the resistance is constant, change the voltage at both ends of the resistor, and observe the relationship between current and voltage; When the voltage is constant, after each change of resistor, adjust so that the voltage at both ends of the resistor remains the same.

Measure the power of the small lamp: adjust the voltage or current of the small bulb to the experimental set value, and measure the electric power under a certain voltage or current.

Measure the lamp resistance.

Measure the electrical power of the bulb.

Used in experiments.

The role of a sliding rheostat.

There are generally two.

Protection circuits. 2. Change the voltage at both ends of the measured object.

Many tests regulate the voltage and current in the circuit.

Reduce errors. Because the length of the sliding rheostat used in the experiment is about 30 cm, the resistance per unit length is small when the resistance is small, and when the resistance is large, the resistance per unit length is large.

When sliding the sliding head, the resistance value is large and the current may be changed because there is no movement, so that it is impossible to distinguish whether the current change caused by movement or the change caused by interference, and the resistance is small, only when the sliding head moves a large distance can cause the current change, so that the error can be reduced.

The role of a sliding rheostat.

1. Change the current in the circuit by changing the resistance of the access circuit part.

2. The protection circuit, that is, the circuit is connected, and before the electric key is closed, the sliding plate P of the sliding rheostat should be adjusted so that the resistance of the sliding rheostat connected to the circuit part is the largest.

There are also some different roles in different circuits, which are described as follows:

1. In the dimmable table lamp circuit, the function of the sliding rheostat is to change the current in the circuit by changing the resistance of the access circuit part.

2. In the relationship between current and voltage, the function of the sliding rheostat is to obtain multiple sets of voltage and current values by adjusting the sliding rheostat, and derive the relationship between current and voltage.

3. In the relationship between current and resistance, the function of the sliding rheostat is to adjust the sliding rheostat to keep the voltage at both ends of the fixed value resistor unchanged, which is the requirement of the control variable method.

1) Sliding rheostat 1: Changing the current by changing the resistance 2: Protecting the circuit.

2) Average measurement of multiple measurements: ** The relationship between the current and resistance of the conductor is measured with a scale to measure the length of the object, and the resistance of the conductor is measured by voltammetry.

3) Summarize the physical laws: the imaging characteristics of plane mirrors, the current characteristics of lever balance bars, and the current characteristics of series or parallel circuits. Through some experimental phenomena, explore and summarize the laws of physics.

Including the melting process of solids, the boiling of water, the sublimation and condensation process of iodine, the law of reflection of light, the imaging characteristics of plane mirrors, the law of refraction of light, the law of lens imaging, the relationship between gravity and mass, the law of two forces synthesis on the same line, the law of internal pressure of liquids, the equilibrium conditions of levers, the relationship between current and voltage and resistance.

Voltammetry measurement value resistance: measure the resistance of Bi Sui many times to reduce the average error.

Voltammetry to measure the resistance of the bulb: measure the resistance of the bulb at different brightness.

Voltammetry side bulb power: measure the power of the small bulb at the same voltage.

Ohm's Law: Two Points 1 The relationship between current and resistance: The voltage at both ends of the control resistor is constant.

2**Relationship between current and voltage: change the voltage at both ends of the resistor.

They all work together: a series of finch flame partial voltage protection circuits.

I choose mine by all means!

The average value of the base brightness is calculated by multiple pulse resistance measurements: the measurement of length and the measurement of resistance.

The sliding rheostat plays a role in several electrical experiments in junior high school: 1. Protection circuit; 2. Change the current; 3. Control voltage.

There are so many physics experiments that it's hard to categorize them for you! The general initial alignment of multiple measurements is used in speed and distance, and the sliding rheostat is mainly used to adjust the voltage of the external circuit.

1. Reduce errors. 2. The size of the resistance can be adjusted according to the experimental requirements.

1. In the voltammetry resistance measurement and measurement of the internal resistance of the power supply, the sliding rheostat is selected.

The maximum value is 2-5 times of the DAO2-5 times of the resistance to be measured, and the current-limiting circuit is adopted.

2. In the volt-ampere resistance measurement and depiction of the volt-ampere characteristic curve of small bulbs, the maximum value of the sliding rheostat is smaller than the resistance to be measured, and the voltage divider circuit is used.

3. In the experiment of using the internal resistance of the ammeter on the half-bias side, the maximum value of the sliding rheostat is more than 100 times of the resistance to be measured, and the current limiting circuit is used.

1.Protects the circuitry, changes the voltage across the resistor under test and the current passing through it (so that multiple measurements can be achieved).

2.Protect the circuit, change the voltage at both ends of the resistor to be measured, and the current passing through it (this allows multiple measurements to summarize the current vs. voltage relationship).

3.Protect the circuit and keep the voltage at both ends of the resistor under test unchanged.

4.Protect the circuit, change the voltage at both ends of the resistor to be measured, and the current passing through it (this allows multiple measurements to summarize the relationship between the brightness of the small bulb and the actual electrical power).

5 and 6 generally do not use sliding rheostats, and if they do, they are also used to protect the circuit and summarize the rules for multiple measurements.