Indique as propriedades de uma fibra ótica que permitem que a luz seja guiada no seu interior com pouca atenuação

d) the number of neutrons plus the number of protons

a charge 3q is at the origin, and a charge −2q is on the positive x axis at x=a. part a where on the x-axis would you place a third charge so it would experience no net electric force? enter an expression for the exact answer, which will involve a square-root sign. (do not enter an approximate decimal answer.)