Red blood cells often become charged and can be treated as point charges. Healthy red blood cells are negatively charged, but unhealthy cells (due to the presence of a bacteria, for example) can become positively charged. In the figure, three red blood cells are oriented such that they are located on the corners of an equilateral triangle. The red blood cell charges are A = 1.90 pC, B = 6.50 pC, and C = -4.80 pC. Given these charges, what would the magnitude and direction of the electric field be at cell A? (1 pC = 1 x 10-12 c.) Magnitude- Direction-

Two tiny conducting spheres are identical and carry charges of - 27.3 µC and + 48.8 µC. They are separated by a distance of 2.43 cm. (a) What is the magnitude of the force that each sphere experiences? (b) The spheres are brought into contact and then separated to a distance of 2.43 cm. Determine the magnitude of the force that each sphere now experiences. (a) Number i Units (b) Number i Units

An outside force, Fo, brings two small metal spheres, A and B, at rest from a long distance away to a point where they are 0.9 meters apart. They are then connected by a non-conducting string of negligible mass. The spheres have mass mA = 5.2 g and mB = 10.4 g and both have equal positive charges of 5 μC. (You may assume the length of the string is much greater than the radii of the spheres.) 1)What was the total work done by the outside force to bring the spheres to the point described? 2)What was the total work done by the electric field when the two sphere were brought together as described? 3)What is the potential energy of the two sphere system after they have been brought together as described? (You may assume the spheres had zero potential energy when they were a long distance apart.) 4)Suppose you cut the string. At that instant, what is the magnitude of the acceleration of sphere A? 5)After a very long time, what is the magnitude of the velocity of sphere A?

Two positive charges are 2 cm apart. One has a charge of 10 µC the other 4 µC. What is the magnitude of the force on each of them from the other? The coulomb constant is 9 x 10° kgm3/s²c2. 900 N 150 N 18 N 80 N