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百度试题 结果1 题目 Radio frequency () waves are a mode of transportation for information and carriers for RF waves are air, copper wire and fiberoptic cable. ( ) 相关知识点: 试题来源: 解析 正确 反馈 收藏
[translate] aMicrowaves, which have a higher frequency than ordinary radio waves, are used routinely in sending thousands of telephone calls and television programs across long distances. 微波,比普通的无线电波有一个更高的频率,在送定期地使用数以万计电话和电视节目横跨长的距离。 [translate] ...
radio-frequency wavesstabilitytransport barrierkinetic theoryThe effect of radio-frequency (RF) waves on negative-energy perturbations (NEPs) is investigated in a straight stellarator within the framework of the Maxwell and drift kinetic theories. It is found that the ponderomotive force and its radial...
Radio waves go through far more cycles in a second than electric current, and we need to use bigger units to measure them. One is thekilohertz(kHz), which is equal to 1000 cycles per second. Another common one is themegahertz(MHz), which is equal to 1,000,000 cycles per second---or...
Radio frequency (RF) refers to the rate of oscillation of electromagnetic radio waves in the range of 3 kHz to 300 GHz, as well as the alternating currents carrying the radio signals. This is the frequency band that is used for communications transmission and broadcasting. Although RF really ...
In the late 1940s, experimenting with high-frequency radio waves, Percy L. Spencer of the Raytheon Company soon invented the microwave (), which made millions of dollars for Raytheon and millions of bags of popcorn for kids everywhere. A.bomb B.prospect C.stove D.oven 相关知识点: 试题来...
What is the wavelength from a radio station having frequency 107.7 MHz? a) 2.790 m b) 27.90 m c) 32.30 m d) 323.0 m Radio waves: Radio waves are electromagnetic waves whose wavelength is more than the infrared rays. Therefore, the frequency of th...
Divided into eight groups, those papers detailing the main developments of the field of HF radio waves are sketched in as condensed a fashion as possible. These groups are full wave theory, geometrical optics and conductivity during the 1950s, the same topics during the 1960s, and full wave ...