Light is not my most favouite topic, but I am forced to do it at school ! Anyway, my homework was to find the refracting index of light in water, air, diamond and perspex. But they said we have to show the working out !!! So can anyone please tell me the speed of light in :- (i) Air (ii) Water (iii) Diamond (iv) Perspex This is urgent !!! I require it in km/s. Thanks !