"Modern Shunfeng Ear─Telephone" Information Transmission PPT Teaching Courseware

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"Modern Shunfeng Ear─Telephone" Information Transmission PPT Teaching Courseware

Part One: Guidance Design

Learning Point 1 Telephone

Question 1: The simplest telephone consists of ________ and ________.

Question 2: As shown in Figure 21-1-2, when speaking into the microphone, due to the vibration of the sound, the diaphragm will press the carbon particles tightly and loosely, and their ________ will change accordingly, flowing through the carbon particles. The ________ of the particles changes accordingly, forming a ________ signal that changes with the sound. There is a __________ inside the earpiece, which attracts a thin iron diaphragm. As the current in the coil continues to change, its effect on the diaphragm also changes, causing the diaphragm to ________, forming sound waves in the air. This way you can hear what the other person is saying.

Question 3: The principle of the telephone is: the microphone converts ________ signals into ________ signals, and the receiver converts ________ signals into ________ signals.

Learning point 2 Telephone exchange

Question 1: Using a telephone switch can ________(optional "increase" or "decrease") line utilization.

Question 2: When making a call, sometimes the line is "busy". At this time, the other party's phone __________ (optional "definitely" or "not necessarily") is in use, but there are too many users wanting to talk between the two switches. .

Learning point 3 Analog signals and digital signals

Question 1: When the microphone converts sound into signal current, the frequency and amplitude changes of this signal current are _____________ with the frequency and amplitude changes of the sound, "imitating" the "every move" of the sound signal. The signal transmitted by this current is called ____________, and the communication method using ____________ is called analog communication.

Question 2: Signals represented by different _______ of different symbols are called __________, and this method of communication is called digital communication.

Question 3: Among analog signals and digital signals, the _____ signal has particularly strong anti-interference ability, so modern telephones have all adopted this signal transmission and processing.

Modern Shunfeng Er Telephone PPT, Part 2: Summary of Frequent Examinations

Type 1 Principle, structure and use of telephone

Example 1: After two phones A and B are connected, which of the following statements is correct ()

A. A's earphone and A's microphone, B's earphone and B's microphone are connected in series in two circuits respectively.

B． A's receiver is connected in series with B's receiver, A's microphone is connected in series with B's microphone

C. A's microphone and receiver, B's microphone and receiver are connected in series in a circuit

D. A's microphone and B's earphone are connected in series in one circuit, and B's microphone and A's earphone are connected in series in another circuit.

[Commentary by Famous Teachers]After two telephones A and B are connected, there are two current paths: one is A’s microphone and B’s receiver forming a current path; the other is B’s microphone and A’s receiver. a current path.

Type 2 telephone exchange

Typical Example 2 When learning the role of a telephone switch in physics class, Teacher Li asked students to discuss in groups and design a model of a telephone switch to realize pairwise calls between five phones. Zhang Yang had a sudden idea and used six classmates in his group to vividly demonstrate the function of a telephone switch. Do you know how they did it?

[Commentary by Famous Teachers]The function of a telephone switch is to enable calls between any two users, minimize the number of lines, and improve line utilization.

Type 3 Analog signals and digital signals

Typical Example 3 As shown in Figure 21-1-8, A is the sound signal waveform, B and C are the current signals transmitted after processing, then among the signals B and C, ________ is an analog signal and ________ is a digital signal.

[Method Breakthrough]The analog signal is continuous, while the digital signal is discontinuous and "jumps". Based on this, combined with the image, it can be determined which signal is the analog signal and which is the digital signal.

Modern Shunfeng Er Telephone PPT, Part 3: Class Feedback

1. Regarding the working process of the telephone, there are the following sentences. The correct order is ()

① The diaphragm suddenly loosens and tightens to squeeze the carbon particles ② When a person speaks into the microphone, sound waves vibrate the diaphragm ③ The resistance of the carbon particles suddenly increases and sometimes decreases ④ The attraction of the electromagnet to the thin iron sheet alternates between large and small, causing the iron sheet to vibrate , the vibration situation is the same as the other party speaking

⑤A current whose intensity changes with the sound is generated in the circuit

A. ①②③④⑤ B. ②①③⑤④ C． ②①④③⑤ D. ①②③⑤④

2. (Multiple choice) Figure 13-1 shows the working diagram of a telephone switch. Regarding telephone exchanges, there are several statements below, the correct one is ()

A. Early telephone exchanges relied on operators to manually wire and disconnect wires.

B． An automatic telephone exchange automatically answers calls through a computer

C. The program-controlled telephone exchange connects the telephone sets through electromagnetic relays.

D. Telephone switches improve line utilization and reduce the number of telephone lines

3. Information communication methods are usually divided into ________ communication and digital communication. ________ communication uses codes composed of different symbols to represent information.

4. Usually digital signals only include _________ different states and are simple in form, so _________ ability is particularly strong and can be easily processed with ___________ and can also be encrypted through different _________.

5. During the process of long-distance transmission and multiple processing and amplification of analog signals, the waveform of the signal current will ________, causing the signal to lose some ________, manifesting as ________ of sound and image. In severe cases, communication will be interrupted.

6． The following table shows some characters and corresponding codes used in digital communication. Please write the code for the word "physical" accordingly and it should be ______________.

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Update Time: 2024-09-28

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

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