How many excess electrons does it have

Two metal spheres, each of radius 2.6 cm, have a center-to-center separation of 2.8 m. Sphere 1 has a charge of +1.2 × 10-8 C; sphere 2 has a charge of -3.3 x 10-8 C. Assume that the separation is large enough for us to assume that the charge on each sphere is uniformly distributed (the spheres do not affect each other). With V= 0 at infinity, calculate in volts (a) the potential at the point halfway between their centers and the potential on the surface of (b) sphere 1 and (c) sphere 2. (a) Number (b) Number i (c) Number i Units Units Units

A 50.2 g ball of copper has a net charge of 2.2 pC. What fraction of the copper's electrons have been removed? (Each copper atom has 29 protons, and copper has an atomic mass of 63.5.)

A 2.5-g copper penny is given a charge of 4.0 × 10−9 C . (a) How many electrons are removed from the penny? (b) If no more than one electron is removed from an atom, what percent of the atoms are ionized by this charging process?

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-

You hold a ruler that has a charge on its tip 4.00 cm above a small piece of tissue paper to see if it can be picked up. The ruler has  −10.0 µC  of charge. The tissue has 1.00 g of mass. What is the minimum charge required to pick up the tissue paper?

Answer the following

Electrons have a charge of q = -1.602 × 10-19 C. A student observes that a Styrofoam cup has a total charge of Q = -0.69 μC. a)Write an expression for the number of excess electrons N in the cup.  b)  How many excess electrons are in the cup?

You hold a ruler that has a charge on its tip 3.80 cm above a small piece of tissue paper to see if it can be picked up. The ruler has –10.0 µC of charge. The tissue paper has 5.00 g of mass. What is the minimum charge required to pick up the tissue paper?

A 53.0 g ball of copper has a net charge of 1.5 µC. What fraction of the copper's electrons have been removed? (Each copper atom has 29 protons, and copper has an atomic mass of 63.5.) Answer: ______________