Eventually, the upgrades could do away entirely with the red, yellow and green lights of today ... Hajbabaie suggests adding a fourth light, perhaps a white one, to indicate when there are ...

W hen you hop in your car to head to work, drop your kids off at school or make a Target run, how many traffic lights do you ...

You can use a prism to split (or disperse) white light into a spectrum of colours: red, orange, yellow, green, blue, indigo and violet. Dispersed means that the colours are separated out.