detailed solution

3. Three identical point charges with charge q = +3.0 x 10* C are placed at each vertex of an equilateral triangle ABC shown. If the side of the equilateral triangle is 0.01 m, find the resultant electric force on the charge at vertex B. (10 points) 4. Four point charges are equally separated by 1.00 m in air. If q, = 3.0 nC.q, = -4.0 nC.q3 = 2.0 nC and 94 = -5.0 nC. what is the electric field at a point halfway between q, and q2? (10 points) 5. A tiny ball weighs 0.0025 kg and carries a charge of +3.25 x 10* C. What is the electric field (magnitude and direction) is needed for the ball to remain suspended in air? (10 points) 6. In the Bohr model of the hydrogen, the electron (-e) is in orbit about the nuclear proton (+e) at a radius of r = 5.29 x 10"# m. Determine the speed of the electron, assuming the orbit to be circular. (10 points)