"How to Understand Resistance" Exploring Ohm's Law PPT Courseware 3

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"How to Understand Resistance" Exploring Ohm's Law PPT Courseware 3

Review question: How can the resistance of a conductor be changed? Which method is easiest?

Methods include changing the _________, _________, _________ and _________ of the conductor. And the most convenient thing is to change _________.

Resistors (resistance) in life

1. Resistor - a component with a certain resistance value

1. The function of a resistor: used to adjust the current in the circuit; protect the circuit.

2. Graphical symbol of fixed value resistor:

2. Rheostat

3. Sliding rheostat

1. Structure of sliding rheostat:

2. Structural diagram and symbols of sliding rheostat

3. Label of sliding rheostat

The maximum resistance value and the maximum current allowed to pass are marked on the label.

4. Principle of sliding rheostat

By changing the length of the resistor wire connected to the circuit, the resistance is changed, thereby changing the current flow.

sliding rheostat

Textbook P75

Activity 3: Understand the sliding rheostat

(1) The marked value of this sliding rheostat is ___Ω. Which two terminals does this value refer to?

(2) The resistance between which two terminals is very small, almost zero?

(3) How does the slider contact the resistance wire?

Pass the slide, which has had its insulation scraped off

(4) For the rheostat shown in the figure, when the slider slides to the right, the resistance between which two terminals becomes larger? The resistance between which two terminals becomes smaller? The resistance between which two terminals does not change?

How to change the resistance of a sliding rheostat connected to a circuit

When the slider moves away from the lower terminal, the resistance of the connected circuit increases.

When the slider is close to the lower terminal, the resistance of the access circuit decreases.

practise

1. In the circuit as shown in the figure, in order to make the brightness of the light bulb smaller, the resistance of the part of the varistor connected to the circuit must be changed to __, the indication of the ammeter changes to ____, and the sliding contact P should move to __.

2. As shown in Figure 1, when the sliding varistor slide moves to the right, which of the following statements is correct ( )

A. The resistance connected to the circuit becomes smaller and the current in the circuit becomes larger.

B. The resistance connected to the circuit becomes smaller, and the current in the circuit becomes smaller.

C. The resistance connected to the circuit becomes larger and the current in the circuit becomes smaller.

D. The resistance connected to the circuit becomes larger, and the current in the circuit becomes larger.

3. Figure 2 is a schematic structural diagram of a sliding rheostat with four terminals. When terminals A and D are connected to the circuit, the slider moves to the right, and the resistance value of the connected circuit is ______. If the nameplate of this varistor is marked with "20Ω1A", it means that the resistance variation range of this varistor is ________, and the maximum current allowed to pass is ___A. When the slider P moves to the midpoint, the resistance R=_____Ω is connected. Connect this varistor to the circuit shown in Figure 3 below. When the slider P moves to the left, the current in the circuit _____.

4. Among the following four connection methods, the connection method is wrong and has no resistance and causes excessive current in the circuit ( ); the one that only functions as a fixed-value resistor and cannot change the current in the circuit ( ).

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"How to Understand Resistance" Exploring Ohm's Law PPT Courseware 2:

"How to Understand Resistance" Exploring Ohm's Law PPT Courseware 2 Teaching Objectives 1. What is resistance, and what factors are related to the size of resistance. 2. What research methods are used to study resistance. 3. How to use sliding rheostat Test preview 1 1. What factors are related to the resistance size..

"How to Understand Resistance" Exploring Ohm's Law PPT Courseware:

"How to Understand Resistance" Exploring Ohm's Law PPT Courseware Learning Objectives 1. Know what resistance is, know the units of resistance, and know the factors that determine the resistance of a conductor. 2. Understand the basic structure and principle of the sliding rheostat, and be able to use the sliding rheostat to change the...

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Update Time: 2024-07-30

This template belongs to Physics courseware Guangdong and Shanghai Edition Ninth Grade Physics Volume 1 industry PPT template

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