Question

A molecule of DNA (deoxyribonucleic acid) is 2.02

Answer 1

Length of the molecule is d = 2.02 ?m =2.02*10^-6m

Now one end it is singly ionized positive and at the other endsingly ionized negative.

Then force between the charges is F =(1/4??₀)(+e)(-e)/d²

e = 1.6*10^-19C

1/4??₀ =9*10⁹Nm²/C²

Then F=-( 9*10⁹Nm²/C²)*(1.6*10^-19C)²/(2.02*10^-6m )²

          =- 5.6465 *10^-17N

Now compression in the length is x = (1.28/100)*d=  (1.28/100)*2.02*10^-6m

Then we know that F = -kx

              - 5.6465 *10^-17N =-k*(1.28/100)*2.02*10^-6m

solve for k (spring constant) =2.1838 *10^-9N/m