Millikan measured the electron's charge by observing tiny charged oil drops in an electric field. Each drop had a charge imbalance of only a few electrons. The strength of the electric field was adjusted so that the electric and gravitational forces on a drop would balance and the drop would be suspended in air. In this way the charge on the drop could be calculated. The charge was always found to be a small multiple of 1.6e-19 C. Find the charge on an oil drop weighing 1.94  10-14 N and suspended in a downward field of magnitude 2.42  104 N/C.    e

A test charge of +1.9 uC is placed halfway between a charge of +4.6 µC and another of +7.4 µC separated by 14 cm. What is the magnitude of the force on the test charge?

Two point charges of magnitude +10 μC and - 30 μC are placed 1 meter from each other. Calculate the magnitude of the Net Force on a proton (charge = 1.6x10-19 C) that is placed directly between the two charges.

Electrostatic force (in Newtons)between two charges is given by the formula, Fe=kq1 q2/r^2, where k is about 9E9. The amount of charge in a AA battery is about 9000 coulomb. Suppose you took two AA batteries and dumped one of the battery's charge in the purple pile and the other battery's charge in the red pile. You place the piles 9 meters apart. What is the electrostatic force between the two charges? (You should be able to do this math in your head) Select: (1E6 N, 7.29E17 N, 8.1E16 N, or 9E15 N) Is this a repulsive or attractive force? Select: (neither, repulsive, or attractive)To increase the magnitude of this force, would you increase or decrease the distance between them? Select: (increase, decrease, or depends on direction)

A system of 1358 particles, each of which is either an electron or a proton, has a net charge of -1.002x10-16 C. How many electrons are in this system (exactly)? Submit Answer Tries 0/32 What is the mass of this system (to three significant digits)?

Based on diagrams in Fig. 2, identify which particle reach the plate first after travelling based on their respective charges and directions. Assuming charge of 1e = 1.6 × 10-19 C, mass of electron 9.1 × 10-31 kilograms and distance between plate for both cases E1 and E2 is 500 cm.

Consider an electron that is 1.10-10 m from an alpha particle with charge 3.2.10-¹⁹ C. (a) What is the electric field due to the alpha particle at the location of the electron? The direction of the electric field by the alpha particle at the electron is Ela ate C (b) What is the electric field due to the electron at the location of the alpha particle? The direction of the electric field by the electron at the location of the alpha particle is #J N C |Ele- at a (c) What is the magnitude of the electric force on the electron? ✔N F = = (d) What is the magnitude of the electric force on the alpha particle? Fa= N (e) Do the two forces obey Newton's Laws?

Two identical point charges of 310 × 10-9 C are separated by a distance of 145 × 10-4 m. Part (a)  Calculate the electrostatic force between these charges.  Part (b)  Assume that the two identical point charges are positioned one above the other, with the electrostatic repulsive force equal to the weight of one of the charges. Assuming that the point charges are of identical mass, calculate the mass of one of the charges in kg.

A pith ball with charge 0.2 mC is brought close to a van der Graaf generator with a charge of 100 mC (500 times that of the pith ball). The pith ball exerts an electric force of 20 mN on the van der Graaf generator. What is the magnitude of the electric force that the van der Graaf generator exerts on the pith ball? Answer in mN.

A hydrogen atom is located close to the surfsce of the earth. a) What is the ratio of the magnitude of the electric force between the electron and proton compared to the magnitude of the gravitational attraction between the electron and proton compared to the magnitude of the gravitational attraction between the electron and the earth? (This is how many times greater the electric force is in this situation) b) Draw a conclusion about the stability of matter. (How come gravity doesn't pull molecules apart?) c) Why is the gravitational force between the Earth and Moon greater than the electric force? (Since all matter is made of protons and electrons, why isn't electric force always greater?)