Along straight wire has fixed negative charge with a linear charge density of magnitude 5.1 nc/m. the wire is to be enclosed by a coaxial, thin-walled, nonconducting cylindrical shell of radius 1.9 cm. the shell is to have positive charge on its outside surface with a surface charge density σ that makes the net external electric field is zero. calculate σ. express your answer in terms of 10-8.

Electric field of the earth. the earth has a net electric charge that causes a field at points near its surface equal to 150 n> c and directed in toward the center of the earth. (a) what magnitude and sign of charge would a 60-kg human have to acquire to overcome his or her weight by the force exerted by the earth’s electric field? (b) what would be the force of repulsion between two people each with the charge calculated in part (a) and separated by a distance of 100 m? is use of the earth’s electric field a feasible means of flight? why or why not?