"Rheostats" PPT

Description

"Rheostats" PPT

Part One: Review

Resistor (symbol: "R")

1. Concept: The hindering effect of conductors on current flow.

The more resistant a conductor is to the flow of electricity, the greater its resistance.

2. Unit: ohm (ohm) (symbol: “Ω”)

Kilo ohms (KΩ), mega ohms (MΩ)

3. Factors affecting conductor resistance:

Conductor material, conductor length, conductor cross-sectional area, temperature

Rheostat PPT, Part 2: Resistor (fixed value resistor)

1. Resistor (also called resistor): a component with a certain resistance value

2. The role of a resistor: to control the current in the circuit.

3. The symbol of the resistor:

A resistor can be connected in series to reduce the current in the circuit

If we want to make the current smaller and the light darker, what should we do?

Connect another resistor in series.

If we want to make the current smaller and the light darker, what should we do?

Connect another resistor in series.

Rheostat PPT, Part 3: Rheostat

1. Rheostat: A resistor that changes resistance value

2. Function: Change the size of the current in the circuit

3.Application:

Change the resistance → change the current → change the effect of electrical appliances

Applications of Rheostats

1. Dimmable desk lamp

2. Volume knob switch

3. Mixer

4. External loudspeaker

5. Electric vehicle speed control knob and electric vehicle brake

Rheostat PPT, Part 4: Sensitive Resistors

1. Sensitive resistor

It refers to a resistor whose device characteristics are sensitive to temperature, light, pressure, gas magnetic field, humidity, etc.

2. Type

Thermistor, photoresistor, varistor, gas-sensitive resistor, magnetoresistance, humidity-sensitive resistor, force-sensitive resistor, etc.

3. Function

The resistance of a photoresistor will decrease rapidly when exposed to light, so it can be used for light measurement, light control and photoelectric conversion.

Automatic lighting control circuit and automatic adjustment of TV brightness.

Force-sensitive resistor is a special component that can convert mechanical force into electrical signal. Its resistance value changes with the magnitude of external force. It is commonly used in various tensiometers, torque meters, accelerometers and various pressure sensors. .

There is a force sensitive resistor in the electronic scale, which can convert the pressure into an electrical signal and display it on the electronic screen.

Rheostat PPT, Part 5: Practice

1. As shown in the figure below, if the wires are connected to the two terminals A and C of the sliding varistor, how will the resistance of the varistor change when the sliding contact P slides to the right? _____. If connected to the two terminals _____ and _____, the resistance value will be the maximum value and will always remain unchanged.

2. As shown in the circuit diagram above, in order to make the brightness of the light bulb smaller, the resistance of the part of the circuit connected to the varistor must change to _____, the reading on the ammeter changes to _____, and the sliding contact P should move toward _____.

3. According to the circuit diagram in Figure 4-43A, connect the components in Figure 4-43B with wires. In what position should the sliding contact of the sliding rheostat slide before the switch is closed? Why?

Before the switch is closed, the sliding contact of the sliding rheostat should slide to the far right.

The position of maximum resistance.

Keywords: Zhejiang Education Edition eighth grade science PPT courseware free download, rheostat PPT download, .PPT format;

For more information about the "Rheistor" PPT courseware, please click the "Rheistor ppt" tab.

"Rheostats" PPT download:

"Rheistor" PPT download Part 1: Knowledge review 1. What physical quantity is resistance? Answer: Resistance is a physical quantity that represents the resistance of a conductor to current; the greater the resistance, the greater the resistance to current. 2. The factors that affect the size of the resistance are...

"Rheostats" PPT courseware:

"Rheistor" PPT courseware part one content: Rheostat 1. Rheostat: Principle of a device used to change the resistance: the size of the resistance changes with the length of the conductor. The maximum resistance value of this sliding varistor is 20, and the maximum current allowed is 2A. ..

"Rheostats" Voltage and Resistance PPT Courseware 2:

"Rheostats" Voltage and Resistance PPT Courseware 2 1. Resistance of the Conductor 1. Resistance: Indicates the resistance of the conductor to the current. 2. The greater the resistance of the conductor, the greater the resistance to the current. 3. The symbol of resistance in the circuit diagram 4. The unit of resistance: ohm symbol 5..

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Update Time: 2024-09-30

This template belongs to science courseware Zhejiang Education Edition Eighth Grade Science Volume 1 industry PPT template

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