Ignorance is No Disgrace

The little brother of an Army radar operator asked，“Jim，tell me how does a radar work？”

“The radar transmitter emits brief impulses of electromagnetic waves which are reflected from the target and received by a special receiver．Since the speed at which electromagnetic waves propagate is exactly known and the time they take to travel to the target and back can be determined with a great degree of accuracy，it is possible to determine the range to the target as well as the direction to it．”

His brother pondered a moment，then said，“As long as you don’t know，Jim，why don’t you just say so？”

无知者无罪

一个雷达兵的小弟弟问他：“吉姆，能告诉我雷达的工作原理吗？”

“雷达发射器发射出短促的电磁波脉冲，被目标反射，由一个特殊的接收器接受。因为电磁波的传播速度可以准确地知道，而且它们传播到目标的时间以及返回的时间都可以在很大程度上准确地知道，因此，可以探测出目标的距离以及目标的方向。”

他的小弟弟思考了一会儿，说道：“既然你不知道，吉姆，为什么你不直说呢？”