"Resistance" Voltage and Resistance PPT Courseware 2

Description

"Resistance" Voltage and Resistance PPT Courseware 2

The wires are mostly made of copper, and the wires of particularly important electrical equipment are also made of expensive silver. Iron is also a conductor. It is abundant and cheap. Think about it, why not use iron as a conductor?

Demo 1

Connect copper wires and nickel-chromium alloy wires of the same length and thickness to the circuit respectively, close the switch, and observe the brightness of the small bulb in the circuit.

Experimental phenomena

By connecting different conductors, the brightness of the small bulb changes.

Demo 2

In the above experiment, connect the ammeter, observe the changes in the ammeter's indication, and continue to observe the brightness of the small bulb.

Experimental phenomena

When the copper wire is connected to the circuit, the ammeter will read larger and the small bulb will be brighter;

When the nickel-chromium alloy wire is connected to the circuit, the ammeter indicates a smaller value and the small bulb becomes darker.

question

Under the same voltage, the current passing through the copper wire is larger than that of the nickel-chromium alloy wire. Why is there this difference?

Experimental phenomena

Although conductors easily conduct electricity, they also have a certain hindrance to current flow.

Under the same voltage, the current passing through the copper wire is relatively large, indicating that the copper wire has a relatively small obstruction to the current;

The current passing through the nichrome wire is relatively small, indicating that the nichrome wire has a relatively large obstruction effect on the current.

1. Resistance

1. In physics, resistance is used to represent the resistance of a conductor to current flow.

The greater the resistance of a conductor, the greater its resistance to current flow. The resistance of a conductor is usually represented by the letter R.

2. Unit: ohm (ohm), referred to as ohm, symbol Ω.

3. The units of resistance are also: megaohm (MΩ) kiloohm (kΩ)

The conversion relationship is:

1 kΩ = 1 000 Ω = 103 Ω

1 MΩ = 1 000 000 Ω = 106 Ω

4. Resistor

In electronic technology, we often use components with a certain resistance value - resistors, also called fixed-value resistors, or resistors for short. Symbols are used in circuit diagrams.

2. Explore the factors that affect the resistance size

Under the condition of certain materials, what other factors are related to the resistance?

Whether the size of the resistance is related to the length of the wire;

Whether the size of the resistance is related to the thickness of the wire;

other factors.

1. Explore the relationship between resistance and conductor length

2. Explore the relationship between resistance and conductor cross-sectional area

practice

1. A conductor is connected to a 3-volt power supply with a resistance of 10 ohms. If the conductor is removed from the circuit, the resistance of the conductor is _______ ohms.

Analysis: The resistance is 10 ohms, which is a property of the conductor itself. It has nothing to do with whether the conductor is connected in the circuit, whether there is voltage at both ends, or whether there is current in it.

2. Briefly answer the following questions:

(1) Why are the insulators of high-voltage lines (as shown in the picture) made of ceramic materials instead of glass?

(2) Iron is cheaper than copper. Why are copper wires used in household circuits instead of iron wires?

(3) Why can’t you operate electrical appliances with wet hands?

3. A and B are two identical wires, each with a length of 1 m. Cut A in half, and compare the remaining half with B. Which one has greater resistance? Stretch the remaining half of A to 1 m. Compared with B, which resistance is greater?

Keywords: Voltage and resistance teaching courseware, resistance teaching courseware, Lujiao version ninth grade physics PPT courseware download, ninth grade physics slide courseware download, voltage and resistance PPT courseware download, resistance PPT courseware download, .PPT format;

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

"The Relationship between Current, Voltage and Resistance" PPT courseware:

"The Relationship between Current, Voltage and Resistance" PPT courseware Part 1: Introduction of the topic Please look at the following experiment and think about the problem. Please think: What can be done to dim the light bulb? Method 1: Remove a battery Method 2: Add resistance to the circuit Question: Same...

"The Relationship between Current, Voltage and Resistance" PPT:

"The Relationship between Current, Voltage and Resistance" PPT Part One Content: Thinking: Which physical quantity is most susceptible to the magnitude of the current passing through a certain conductor in a certain circuit, the voltage at both ends of this conductor, and the resistance of this conductor, which physical quantity is most susceptible to the other two Due to changes in quantity...

"Conductivity and Resistance of Matter" PPT download:

"Conductivity and Resistance of Matter" PPT Download Part One: Life Examples Which objects in life easily conduct electricity? Which ones don’t conduct electricity easily? Coins, plastic rulers, glass pieces, pencil lead, salt water, chalk, purified water. How to design an experiment? 1. Judgment criteria..

File Info

Update Time: 2024-09-11

This template belongs to Physics courseware Lu Jiao Edition Ninth Grade Physics Volume 1 industry PPT template

Preview