concave mirror

基本解释

The diameter of a sphere is four times the focal length of a concave mirror cut from it.
凹面镜如果是从圆球上切下来的，圆球的直径会是凹面镜焦距的四倍。
Cool Earth’s insight was that if you coat only one half of a balloon, leaving the other transparent, the inner surface of the coated half will act as a concave mirror.
Cool Earth的想法是如果你只镀半个气球，另一半是透明的，镀层内表面的那半起凹透镜的作用。
Cool Earth's insight was that if you coat only one half of a balloon, leaving the other transparent, the inner surface of the coated half will act as a concave mirror.
酷地太阳能公司有个独到的认识：如果只给气球的一半涂上金属，让另一半透光，那么涂有金属的那一半内表面就会象一个凹面镜。

Cool Earth's insight was that if you coat only one half of a balloon, leaving the other transparent, the inner surface of the coated half will act as a concave mirror.
ECONOMIST: Monitor