Question

Two positive charges distant 0.1m apart, repel each other with a force of 18N.If the sum of the charges be 9 micro-coulomb,then calculate their separate values. PLZZ SOLVE THE QUADRATIC PART

Answer 1

According to Coulomb's law the force between them can be given as F = K Q1 Q2/ r ^2. 18 = 9 × 10^9 × Q1 × Q2/ 10^-2. Q1 × Q2 = 2 × 10^ -11. Q1 + Q2 = 9×10^-6. Q1= 9×10^-6 - Q2. THERFORE (9×10^-6-Q2)× Q2 = 2 × 10^-11. Let Q2 BE X. THERFORE X^2 - 9×10^-6X + 2×10^-11. X^2 - 9×10^-6X + 20×10^-12. X^2 -5×10^-6 - 4×10^-6 + 20×10^-12. X ( X - 5×10^-6 ) -4 ×10^-6 ( X - 5×10^-6). THEREFORE X = Q2 = 5 ×10^-6 C = 5 MICRO COULOMB OR X = C = 4 ×10^-6 C = 4 MICRO COULOMB. Therefore two charges are 4 and 5 micro coloumb.