There are upsetting parallels today, as scientists in one wave after another try to awaken us to the growing threat of global warming. The latest was a panel from the National Academy of Sciences, enlisted by the White House, to tell us that the Earth’s atmosphere is definitely warming ...
A. It can travel in a vacuum. B. Its speed depends on the frequency. C. It has a wavelength and frequency. D. It doesn't need a medium to propagate. 相关知识点: 试题来源: 解析 C。本题考查声波的特征。声波具有波长和频率,选项 C 正确。选项 A 声波不能在真空中传播,选项 B 声波速度...
When a sound wave travels through the air, it causes the air molecules to vibrate ___ a certain frequency. A. at B. in C. on D. with 相关知识点: 试题来源: 解析 A。“以……频率振动”用 at a certain frequency,固定搭配。in 表示“在……里面”;on 表示“在……上面”;with 表示“...
结果1 题目 When we speak, the sound wave can be treated as a spherical wave. The sound level is measured lower for a longer distance to the speaker, because the intensity of sound wave decreases over distance.A.正确B.错误 相关知识点: 试题来源: 解析 A 反馈 收藏 ...
由题干关键信息“sound wave vibrations”“the first two paragraphs”可快速定位至前两段,根据这两段的内容,尤其是第二段中的“Since the 1940s,scientists have investigated the technology of acoustic levitation, the use of sound wave vibrations to trap tiny things in midair.”可知,声波振动可以用来...
28. The finding of the study can be best described as ___ according to the first paragraph. A. a widely accepted belief. B. something surprising. C. a wholly resisted opinion. D. something still in debate. 29. ...
国外物理题(概念),关于声波的We cannot see a sound wave.However we can see a representation of it by connecting a microphone to———(b) The pitch of a sound depends on———(c) The loudness of a sound depends on———第二个问题哈:A wire carries a current.The wire is perpendicular ...
7 A sound wave has a time period T. The diagram shows the positions at time t of air layers which have been displaced by the passage of the wave. At this time there is a rarefaction at position X.X At time t + At there is a compression at position X.At may be equal to B口A...
Based on the figure, does S depend on the frequency of a sound wave of a given intensity? A. Yes, because as frequency increases, S increases. B. Yes, because as frequency increases, S remains constant. C. No, because as frequency increases, S increases. D. No, because as frequency ...
8Sound travels as a wave.(a) Complete each sentence.Sound is produced when an object...vibrates An echo is produced when sound is ...reflected... from a hard surface.Compared with a quiet sound, a loud sound always has a greater...amplitude Compared with a high pitched sound, a low...