A unit scale is to be prepared whose length does not change with temperature and remains 20 cm, using a bimetallic strip made of brass and iron each of different length. The length of both components would change in such a way that difference between their lengths remains constant. If length of brass is 40 cm and length of iron will be ______cm. (αiron = 1.2 × 10-5 K-1 and αbrass = 1.8 × 10-5 K-1).
