"Rheistor" voltage resistance PPT

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"Rheistor" voltage resistance PPT

Part One Content: Basic Knowledge Key Points

Knowledge point 1 Rheostat

1. The sliding rheostat changes the resistance by changing the length of the resistance wire in the circuit. As shown in the figure, the nameplate of the sliding rheostat in the circuit has the words "10 Ω 2 A". In order to change the current in the circuit to the greatest extent, The measuring range of the ammeter should be 0~3 A; during the sliding process of the slide plate P, the slide plate P cannot (optional "can" or "cannot") move to the leftmost position a.

2. (Huaihua High School Entrance Examination) As shown in the figure, when the slider slides to the left, the resistance connected to the circuit becomes larger (D)

3. (Jiaxing High School Entrance Examination) As shown in the picture, the circuit is not connected completely. If the switch is required to be closed, when the slide P of the sliding rheostat moves to the left, the light bulb will light up. Then the following connection method meets the requirements: (A)

A.M connects to A, N connects to D B.M connects to B, N connects to C C.M connects to A, N connects to B D.M connects to C, N connects to D

Knowledge point 2 Application of rheostat

4. (Shenyang High School Entrance Examination) As shown in the figure, A is a desk lamp with adjustable brightness, and the potentiometer is a device for adjusting its brightness; B is a schematic diagram of the internal structure of the potentiometer, and a, b, and c are its three terminals. The knob drives the slide to rotate. If the bulb glows brighter when you turn the knob clockwise, you need to connect the b and c (optional "a and b", "a and c" or "b and c") terminals to the circuit. Regarding the material of the resistance wire on the potentiometer, nickel-chromium alloy wire should be used (optional "copper wire" or "nickel-chromium alloy wire").

5. The picture below is a schematic diagram of a large electronic floor scale. When weighing a heavy object, the sliding plate P slides downward under the action of pressure, the resistance of the rheostat connected to the circuit becomes smaller, and the indication of the ammeter becomes larger (choose "increase", "become smaller" or "unchanged") .

Rheostat PPT, part 2: improvement of comprehensive capabilities

6. As shown in the figure, if the two terminals A and C are connected to the circuit, when the slider P moves to the right, the resistance value of the part of the sliding rheostat connected to the circuit becomes larger; if only two terminals A and B are connected, The binding post is equivalent to connecting a fixed value resistor to the circuit.

7. The resistance box shown in the figure shows 2098Ω.

8. In the circuit as shown in the figure, in order to change the current in the circuit, M and N can be connected to the B and D terminals of the sliding rheostat. After closing the switch, when P slides to the right, the current in the circuit will get bigger. When M and N are connected to the A and C terminals of the sliding rheostat, and P slides to the left, the current in the circuit will increase. When P slides to terminal B (optional "A" or "B"), The current in the circuit is minimal.

9. In the circuit as shown in the figure, the resistance line of the varistor connected to the circuit is the Pb (optional "aP", "Pb" or "ab") part. When the liquid level in the fuel tank drops, the resistance in the circuit will becomes larger, the current indication number becomes smaller (choose "increase", "unchange" or "get smaller").

10. (Weifang High School Entrance Examination) The picture below shows the four situations in which the sliding rheostat is connected to the circuit after the experimental circuit is connected. The switch can be closed for experiment (A)

Rheostat PPT, the third part: Expansion, exploration and breakthrough

14. After Xiao Ming learned about the rheostat, he went to the laboratory to do an experiment in which he used a sliding rheostat to adjust the brightness of a small light bulb, and at the same time observed the relationship between the brightness of the small light bulb and the voltage at both ends and the passing current. The picture shows Xiao Ming’s unfinished circuit design.

(1) Please use stroke lines instead of wires to complete the unfinished circuit in the picture, and make the small bulb dim when the sliding rheostat slide moves to the right (wires are not allowed to cross);

(2) When connecting the circuit, the switch should be in the "off" state;

(3) After connecting the circuit and closing the switch, the slider of the sliding rheostat should be placed at terminal B (optional "A" or "B");

(4) After closing the switch, it is found that the small bulb does not light up, the voltage indication is zero, and the ammeter pointer deflects normally. The reason for this phenomenon may be D.

A. Small light bulb is broken B. Sliding rheostat is broken

C. Short circuit of sliding rheostat D. Short circuit of small light bulb

15. The resistance of a certain sliding rheostat can vary between 0 and 20 Ω. The clever student Wenwen wants to use the circuit diagram as shown in the figure to find the midpoint position of the sliding rheostat through experiments.

(1) Close the switch S, move the sliding plate of the sliding rheostat, and observe the two voltage indications. When they are equal, the position of the sliding plate is the midpoint position of the sliding rheostat. This is based on the principle of series voltage division. judgmental;

(2) If you still want to know the changes in current in the circuit, you need to connect an ammeter in series with the circuit and add a wire.

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For more information about the "Voltage Resistor Rheostat" PPT courseware, please click on the Voltage Resistance ppt Rheostat ppt tag.

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Update Time: 2024-09-24

This template belongs to Physics courseware People's Education Edition Ninth Grade Physics Complete Book industry PPT template

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