What is the significance of the -ve sign in W = -mgd?

The total energy of the electron in an hydrogen atom is En = -13.6/n^2 eV What is the significance of the negative sign?

What is the significance of meiosis?

What' is the significance of null vector?

What is the significance of Lewis symbols?

What is the significance of the slope of x-t graph

What is the significance of Gauss law in magnetism?

What is the significance of leaching in the extraction of aluminium?

What is the significance of Newton's second law of motion ?