看把电灯泡的玻璃罩子去掉了，分别在空气中和液氮中通电后会发生什么。
What happens if you remove the glass on a lightbulb and switch it on, in air and in liquid nitrogen.
In air, the bulb quickly burns out as there is nothing stopping oxygen getting to the filament, meaning it burns rapidly.
In liquid nitrogen, the bulb stays lit up because the liquid nitrogen pushes the oxygen away from the filament, meaning it’s not immersed in oxygen so burns more slowly.
Watch the whole demo in the 2014 Christmas Lectures, available on the Ri Channel for free.
