A magnet keeps a cabinet door closed. The Sun pulls on Earth as Earth moves around the Sun. The protons in the nucleus of a carbon atom are held together.So this is an example of the strong force in action.
You asked about strong force, the strong force keeps quarks together in clusters to make more-familiar subatomic particles, such as protons and neutrons.
Gel electrophoresis is a process or a technique in which fragments of DNA are separated in terms of their sizes.
<em><u>The restriction enzyme is mixed with a DNA sample before the process. The restriction enzyme cut DNA at specific points into fragments which can then be separated based on their sizes on an agarose gel.</u></em>
When current is applied to the gel DNA move towards the positively charged electrode since DNA is negatively charged, with shorter fragments migrating faster through the gel in comparison with large fragments.
