Question

why it became necessary to redefine metre on atomic standard please ans me fast tommorow is my exam . no spam are required
​

Answer 1

Answer:

It became necessary to redefine metre on atomic standard because the prototype metre offered the following difficulties: (i) It is difficult to preserve a metre bar. (ii) It is difficult to produce replicas of metre bar for their use in different countries. (iii) The techniques used for producing replicas are not of very high accuracy.