Inks that respond to sunlight are called photochromic inks. Variations in the level of ultra violet light determine the colour they display. A possible application of this type of ink is a commemorative stamp designed to promote solar power. The colour scheme of the stamp could change as the stamp is moved from natural light (sun light) to artificial light (electric light bulb / fluorescent strip light).

1. Complete the two basic stamp layouts below, adding more detail and colour. Stamp ‘A’ should show how the stamp looks in natural light (sun light) and stamp ‘B’ should show how the stamp has changed when placed under artificial light (electric light bulb / flourescent strip light).

2. Complete the blank stamp below by drawing a design of your own. The stamp must commemorate any form of alternative energy and use any one type of smart ink.