The Doppler effect (or Doppler shift), named after Austrian physicist Christian Doppler who proposed it in 1842 in Prague, is the change in frequency of a wave for an observer moving relative to the source of the wave. It is commonly heard when a vehicle sounding a siren or horn approaches...
The number of complete occurrences per unit time is referred to as the frequency. The unit of frequency is Hertz, named after the German physicist Heinrich Hertz.
频繁地,经常→frequency n.出现次数;频繁;频率 7.prefer vt.较喜欢,更喜欢→preference n.偏爱,偏好;更喜欢的人(或物);优待,优先(权) 8.creative adj.创作的,创造性的;有创造力的→create vt.创造,创作→creation n.创造,创建;作品,创作 9.perform vi.表演;工作,运转 vt.表演;做,履行→performance n....
Part of the naming and ranking process will include defining exactly what a heat wave is. No single definition currently exists. Without a universally accepted definition of a heat wave, “We don’t have a common understanding of the danger we face,” says Aaron Bernstein, an expert of the...
Radio having a recording and reproducing unit responsive to a radio wave of a predetermined frequencySetsuo Okada
IN spite of the great theoretical advantages of recording spectra in terms of frequency or wave number, most data on visible and ultra-violet spectra, more particularly spectra of solutions, are in practice expressed as wave-lengths with the millimicron as a favourite unit. One reason for this...
重点短语典型句式核心单词拓展单词英 语必修 第二册 briefly creation create preference frequency frequently UNIT 1 Lights,camera,action!重点短语典型句式核心单词拓展单词英 语必修 第二册 performance performer location located personal personally majority UNIT 1 Lights,camera,action!重点短语典型句式核心单词拓展...
1. What do we know about the heat wave in America? A.It causes most serious physical damage. B.It has got more attention in recent years. C.It kills more people than other natural disasters. D.It is the biggest killer among weather-related disasters. ...
Is the pendulum used in a pendulum clock s... 02:38 Define the term oscillation 01:42 Define the term amplitude of a wave. Write its S.I. unit. 01:44 Define the term frequency . 01:25 Define the term time period as related to a simple pendulum. 01:41 Draw a neat diagram of a...
(temporary)inthepouchforaphaseofsevenoreightmonths.Atlicensedzoos,koalas5.___(hang)ontotreetrunkscanbetouchedforonlyalittletimeandonalimitedfrequencyofoccasions.Aprimitivemammalwith6.___uniquebiology,theduck-billedplatypuswilllayeggsinanest,whichcanhatchintendays.Ithasthecapacity7.___(find)foodbyusingele...