$7\mathrm{.}1$ To provide some perspective on the dimensions of atomic defects, consider a metal specimen that has a dislocation density of $10*$ mm$.$ Suppose that all the dislocations in $1000$ mm$\text{'}(1$ cm$\text{'})$ were somehow removed and linked end to end. How far $($in miles$)$ would this chain extend? Now suppose that the density is increased to $1010$ mm$?$ by cold working. What would be the chain length of dislocations in $1000$ mm$\text{'}$ of material?