This depends on the precise radio frequency of the 21-cm wavelength, or 1420 megacycles per second.
这取决于 21 厘米波长或每秒 1420 兆周的精确无线电频率。
英语百科
Cycle per second
(重定向自Megacycle)
The cycle per second was a once-common English name for the unit of frequency now known as the hertz. The plural form was typically used, often written "cycles per second", "cycles/second", "c.p.s", "c/s", "~" or just "cycles". The term comes from the fact that sound waves have a frequency measurable in their number of vibrations, or cycles, per second.
近义、反义、联想词
近义词
n.
rate
联想词
watt瓦特;frequency频繁;VHF甚高频;
英英词典
megacycle n.
one million periods per second
synonymous: megahertz, MHz, megacycle per second, Mc