by Colin McIntosh, The Cambridge English Dictionary is constantly being updated and expanded to reflect the interests of our users. One area of particular interest to our users is that of English Language Teaching (ELT), and a number of ELT terms have recently been added to the dictionary.y Colin McIntosh, The Cambridge English Dictionary is constantly being updated and expanded to reflect the interests of our users. One area of particular interest to our users is that of English Language Teaching (ELT), and a number of ELT terms have recently been added to the dictionary.
A diode is a one-way âvalveâ for electric current, analogous to a check valve for those familiar with plumbing and hydraulic systems. Ideally, a diode provides unimpeded flow for current in one direction (little or no resistance), but prevents flow in the other direction (infinite resistance).
Optic flow is the perceived visual motion of objects as the observer moves relative to them. To an observer driving a car, a sign on the side of the road would move from the center of his vision to the side, growing as he approached.If he had 360 degree vision, this sign would proceed to move quickly past his side to his back, where it would shrink. This motion of the sign is its optic flow.This allows a person to judge how close he is to certain objects, and how quickly he is approaching them.o an observer driving a car, a sign on the side of the road would move from the center of his vision to the side, growing as he approached. If he had 360 degree vision, this sign would proceed to move quickly past his side to his back, where it would shrink.