A solid prismatic rod is 
          "{L_i}" = 
          
          350 mm
          long and has a circular cross section with a diameter of 
          d = 
          
          40 mm
          
          .
          After the temperature of the unconstrained rod is increased, its final length is measured as 
          "{L_f}" = 
          
          350.135 mm
          .
        
1. Determine the change in the rod's diameter after the temperature increase.