Physics Electrostatics Level: High School
A certain charge Q is divided into two parts q and Q – q , which are then separated by a certain distance . What must q be in terms of Q to maximize the electrostatic repulsion between the two charges ?
Physics Electrostatics Level: High School
Two identical conducting spheres , fixed in place , attract each other with an electrostatic force of 0.108 N when separated by 50.0 cm , center to center . The spheres are then connected by a thin conducting wire . When the wire is removed , the spheres repel each other with an electrostatic force of 0.0360 N . What were the initial charges on the spheres ?
Physics Electrostatics Level: High School
Two equally charged particles , held 3.2 x 10^-3 m apart , are released from rest . The initial acceleration of the first particle is observed to be 7.0 m/s^2 and that of the second to be 9.0 m/s^2 . If the mass of the first particle is 6.3 x 10^-7 kg , what area) the mass of the second particle ?
b) the amount of charge on each particle ?
Physics Electrostatics Level: High School
What distance between point charge qa = 26.0 micro C and point charge qb = 47.0 micro C will the electrostatic force between them have a magnitude of 5.70 N ?
Physics Electrostatics Level: High School
Two identical point charges (Q = 3 micro C) are suited 60 cm apart on the y-axis equidistant from the origin . A 2 micro C point charge lies 40 cm on the “+” x-axis . What is the magnitude and direction of the net force on the 2 micro C charge ?
Physics Electrostatics Level: High School
Consider a vertical parallel-plate capacitor with a system of two masses m1 = 15 g and m2 = 10 g suspended by threads as in the figure at ‘click here’ . The masses are charged with charges q1 = -3 micro C and q2 = +2 micro C . The electric field between the plates is E = 10^4 N/C and the system is in equilibrium . Denote theta 1 the angle made with the vertical by the thread connecting m1 , and denote theta 1 the angle made with the vertical by the thread connecting m2 to m1 .a) Draw the free body diagrams for the two masses . Label the forces .
b) Write Newton’s 2nd Law for each free body diagram along the x and y directions. You will obtain 4 equations . Write the electric forces in terms of the field E .
c) Calculate the angle theta 1
d) Calculate the angle theta 2
Physics Electrostatics Level: High School
The electric field at the Earth’s surface can increase to about 10^4 v/m under thunderclouds . Assume the clouds are 1.0 km above the Earth’s surface .a) How large a potential difference between the ground does that imply ? Is that a voltage you want to experience personally ?
b) A set of lightning strokes can transfer as much as 50 coul of charge . How much energy in the form of heat , light , and sound is released in such a discharge ?
Physics Electrostatics Level: High School
An electric field strength of about 3 x 10^6 volts / meter is needed to produce a spark in air . If placing your finger about 6.0 centimeters from the Van de Graff generator produce a spark , What electric potential difference (voltage) exists at this point ?
Physics Electrostatics Level: High School
The gap between the electrodes in a automobile spark plug is about 1.0 millimeters . If the voltage produced between them is 12000 volts . What is the electric field strength in the gap ?
Physics Electrostatics Level: High School
What is the potential difference between two points in an electric field if 6 x 10^-4 Joules of work is required to move a charge of 2 x 10^-5 coul against the field ?
Physics Electrostatics Level: High School
The earth doe not have neutral charge ……. It’s stocked with lots of extra electrons . An electric field strength of about 100 N/coul (directed downward) exists as the surface of the earth . The radius of the earth is 6.4 x 10^6m .a) How many coulombs of net charge does the earth possess ?
b) Because the earth is a conductor , most of the net charge is on the surface . Use the formula for the surface area of a sphere to find the average amount of net charge on each square meter of earth’s surface .
Physics Electrostatics Level: High School
Electrons not only have charge ; they also have mass . So while they repel each other electrically , they attract each other gravitationally .a) Calculate the repulsive electric force between two electrons placed 10^-10 m apart .
b) Calculate the attractive gravitational force between the same two electrons if the mass of an electron is 10^-30 kg .
c) Which force is greater ………. How many times greater ?
Physics Electrostatics Level: High School
The charge on one electron is 1.6 x 10^-19 coulombs . How much total charge is there on :a) one million electrons ?
b) one billion electrons ?
c) one trillion electrons ?
d) How many electrons are required to make 1 coulomb of charge ?
Physics Electrostatics Level: High School
A van de Graff generator builds up a charge of 6 x 10^-5 coulombs . A second metal sphere Q2 of equal dimensions is touched by the generator . Then Q2 is touched by a third identical sphere Q3 . Calculate the electric force between Q3 and the generator if they are placed 50 cm apart .
Physics Electrostatics Level: High School
Gauss’s Law
A sphere of radius R has total charge Q , The volume charge density (C/m^3) within the sphere is p(r) = C/r^2 , where C is a constant to be determined .a) The charge within a small volume dV is dq = pdV . The integral of pdV over the entire volume of the sphere is the total charge Q. Use this fact to determine the constant C in terms of Q and R . (Hint : Let dV be a spheric shell of radius r and thickness dr . What is the volume of such a shell ?
b) Use Gauss’s law to find an expression for the electric field E inside the sphere , r <= R .
c) Does your expression have the expected value at the surface , r = R ? Explain .
