"Let Information "Fly"" into the information age PPT courseware

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"Let Information "Fly"" into the information age PPT courseware

1. Classification and application of electromagnetic waves

1. Classification: According to ______ from large to small (______ from small to large), it can be divided into: long wave, medium wave, short wave, microwave, ______, visible light, ______, ______, γ rays.

2. Application: Doctors use ______ to perform brain surgery; use ______ to determine whether there is a fracture; remote controls for televisions, air conditioners and other equipment are ______ remote controls, etc.

2. Characteristics of electromagnetic waves

1. Wavelength (λ): the distance between two adjacent wave crests (or troughs). unit:______().

2. Frequency (ν): represents the number of vibrations per unit time. Unit: ______(), commonly used units are ______(), ______(). 1 kHz=______Hz;1 MHz=______kHz=______Hz.

3. Wave speed (c): How fast the wave propagates. unit:______. The propagation speed of electromagnetic waves in vacuum is: c=____________.

4. The relationship between wavelength, frequency and wave speed: ____________.

electromagnetic waves

(1) Generation: Rapidly changing current can produce electromagnetic waves. Theoretically speaking: there is an electric field around a changing magnetic field, and a magnetic field exists around a changing electric field. The alternating alternating electric and magnetic fields form electromagnetic waves.

(2) Classification: People divide electromagnetic waves into gamma rays, X-rays, ultraviolet rays, visible light, infrared rays and radio waves according to their different wavelengths or frequencies.

(3) Application: Electromagnetic waves are widely used. γ rays can be used for brain surgery and checking for cracks inside metals; Used in communications, radar, television, satellite, navigation and other fields.

(4) Features: ① Propagation does not require a medium; ② The relationship between wavelength, wave speed and frequency: c=λν.

Knowledge points electromagnetic waves

1. Which of the following are electromagnetic waves ()

A. Radio waves B. Ultrasonic waves

C. Infrasound waves D. Water waves

2. Which of the following statements about electromagnetic waves is correct ()

A. Electromagnetic waves cannot propagate in vacuum

B. The propagation speed of electromagnetic waves in the air is 340 m/s

C. Visible light is electromagnetic wave

D. Ultrasonic waves are electromagnetic waves

3. Electromagnetic waves propagating in vacuum have the same ()

A. Wave speed B. Wavelength C. Frequency D. Energy

4. The fourth largest pollution after air pollution, water pollution and noise pollution is ()

A. White pollution B. Electromagnetic pollution

C.Light pollution D.Traffic pollution

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"Let Information "Fly"" Entering the Information Age PPT Courseware 2:

"Let Information Fly" Entering the Information Age PPT Courseware 2 Situation Introduction It is impossible to use wires to communicate between the pilots on the plane and the ground commanders, so how are they connected? We listen to the radio or watch TV every day, and there are no wires directly leading to the radio or...

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Update Time: 2024-09-25

This template belongs to Physics courseware Shanghai Science Edition Ninth Grade Physics industry PPT template

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