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Anonymous users2024-02-06Sliding rheostats.
Principle of changing voltage:
The resistance is changed by changing the length of the resistance line of the access circuit part, so as to gradually slide the resistance wire of the rheostat is generally to change the current in the circuit, and the metal rod is generally a metal with small resistance, so when the resistance cross-sectional area is constant, the longer the resistance wire, the greater the resistance, the shorter the resistance wire, the smaller the resistance.
The role of sliding rheostats in circuits:
1) Protection circuit, that is, connect the circuit, before the switch is closed, the sliding blade P of the sliding rheostat should be adjusted so that the resistance of the sliding rheostat connected to the circuit part is the largest.
2) Change the current in the circuit by changing the resistance of the access circuit part, thereby changing the voltage at both ends of the conductor (electrical appliance) connected in series. When connecting the sliding rheostat, it is required: one up and one down, each with a binding post; The actual connection should be selected according to the requirements of the following binding posts.
In addition, we often use knob-type rheostats in our daily life, potentiometers that can adjust the volume.
The knobs that adjust the brightness of the lamp, etc., all work similarly to the working principle of a sliding rheostat.
Connection: The sliding rheostat can be used as a current limiter or a voltage divider in the circuit. Under the condition of ensuring safety, the choice of these two different forms is determined by the needs in the circuit.
The current-limiting connection method can be used in the following cases:
Current-limiting: The resistance of the electrical appliance to be tested is close to the resistance of the sliding rheostat (the voltage divider connection method can also be selected).
Simplify the circuit and save energy.
Voltage divider: The voltage divider connection must be used in the following cases: The resistance of the electrical appliance to be tested is much greater than or much smaller than the resistance of the sliding rheostat. The experiment requires that the current of the electrical appliance to be measured and the voltage at both ends can change continuously from 0 (e.g., the volt-ampere characteristic curve of a small light bulb.
The experiment requires a large variable range of electrical current and voltage at both ends of the electrical appliance to be measured. When the current-limiting connection method is adopted, no matter how the rheostat is adjusted, the current and voltage are greater than the range of the corresponding meter.
The formula for string dividing pressure: u1 u2=r1 r2
and shunt the formula: i 1 i 2 = r2 r1
in a parallel circuit.
, the reciprocal of the total resistance in the circuit is equal to the sum of the reciprocal of the resistance on each branch.
The formula is: r string = r1 + r2 + r3 + .rn
The formula is: 1 r and = 1 r1 + 1 r2 + .1/rn
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Anonymous users2024-02-05The sliding rheostat can change the resistance of the connected circuit, when the sliding rheostat has a current passing through, it can be seen from the Ohm's law formula U=IR of some circuits that the voltage U changes after the resistance R changes; From the Ohm's law formula i=e (in r+r) of the whole circuit, it can be seen that the change of resistance r will cause a change in the current i, and by e=u+ir, when i changes, the voltage u will change
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Anonymous users2024-02-04First of all, correct a little, slide the rheostat.
It is possible to change the voltage at both ends of the electrical appliance connected to it, but not the power 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 is determined by Ohm's law.
It can be known that if the total voltage does not change, 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.
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Anonymous users2024-02-03The reason why the sliding rheostat can regulate the voltage: The sliding rheostat is an important element in the circuit, which can change its resistance by moving the position of the sliding blade, so as to play the role of controlling the circuit.
The functions are as follows: 1. The current in the circuit can be changed by changing the resistance of the access circuit part, so as to change the voltage at both ends of the conductor (electrical appliance) connected in series. When connecting a sliding rheostat, it is required:
One up and one down, the focus is on the bottom", a binding post is used for each metal rod and resistance wire; The actual connection should be selected according to the requirements of the two binding posts of the resistance wire.
2. Pray for the function of the protection circuit, that is, before connecting the circuit and opening and closing, 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 maximized.
3. The voltage can be changed. **Ohm's law, it plays the role of changing the voltage of the two hidden ends of the electrical appliances connected in series.
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Anonymous users2024-02-021.How it works
Because of the sliding rheostat.
It can change the resistance of the connected circuit, and when there is a current passing through the sliding rheostat, the Ohm's law of the part of the circuit.
The formula U=IR shows that the change of resistance R will cause the change of voltage U; From the Ohm's law formula of the whole circuit i= r+r), it can be seen that the change of the current i will be caused by the change of the first hole of the resistor r bridge, and it can be seen from =u+ir that when i changes, the voltage u will change, in addition, the active contact of the sliding rheostat can contact with different potential points, so the sliding rheostat can change the electrosensitive dead voltage. As shown in the figure below, if P moves to terminal A, the voltage at both ends of the load increases, and if P moves to terminal B.
move, the voltage at both ends of the load decreases.
2.Analysis of the working principle of three different circuit connection situations Series and parallel circuits.
, the resistance of the sliding rheostat changes, and the voltage division in series and the shunt principle in parallel: series circuit.
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.
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Anonymous users2024-02-01The sliding rheostat is an important element in the circuit, which can change its resistance by moving the position of the sliding blade, so as to play the role of controlling the circuit. A sliding rheostat is connected in series with a constant resistor at both ends of a constant voltage power supply. When the sliding rheostat slider moves, the resistance value of its own access circuit changes, resulting in a change in the total resistance of the circuit, which can be seen from Ohm's law, the total voltage does not change, the total resistance changes, and the total current will inevitably change.
The function of the slide balance dynamic rheostat is as follows: 1. The current in the circuit can be changed by changing the resistance of the access circuit part, so as to change the voltage at both ends of the conductor (electrical appliance) connected in series. When connecting a sliding rheostat, it is required:
One up and down, the focus is on the bottom", the gold bai rod and the resistance wire each use a terminal as a column; The actual connection should be selected according to the requirements of the two binding posts of the resistance wire.
2. Pray for the function of the protection circuit, that is, connect the circuit, and before the switch is closed, the sliding blade P of the sliding rheostat should be adjusted to maximize the resistance of the sliding rheostat connected to the circuit part.
3. The voltage can be changed. Ohm's law, which plays a role in changing the voltage at both ends of the electrical appliance in series with it.
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Anonymous users2024-01-311. The sliding rheostat is connected in series with a fixed value resistor at both ends of the power supply with constant voltage. When the sliding rheostat slider 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 from Ozen'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.
2. Then apply Ohmher's law to the fixed value resistance: the resistance value of the fixed value resistance does not change, and the current through it changes, so that the voltage at both ends of the fixed value resistance will inevitably change. In this way, the sliding rheostat achieves the effect of changing the voltage at both ends of the fixed value resistor.
3. The sliding rheostat is a circuit element, which can change its own resistance, so as to play the role of controlling the imperial circuit. In circuit analysis, a sliding rheostat can be used either as a fixed-value resistor or as a variable-value resistor.
The resistance box changes the resistance by changing the size and number of resistors connected to the circuit, but because the resistors are one by one, such as many resistance boxes have 1000 ohm gears, 100 gears, 10 gears, and 1 gear, you can get the integer numerical resistance of 0-9999 ohms by adjusting it and know the resistance connected to the circuit, but you can't get the decimal value. The sliding rheostat is continuously variable and can obtain arbitrary resistance within the range, but the exact value cannot be known.
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