Question

Mr. Weinstock ExamI Directions: Answer question ONE and 4 of the remaining 5 problems. Show all work. Partial credit granted 1 Define, describe, or draw a diagram to explain the following terms (a) lines of force; (b) conservative force; (c) electric potential: (d) dielectric; (e) flux. 1. An electron is located at the origin whose q- -1.6 x 1019 Coul and whose mass is 9.11 x 103 kg is in an E-field, E -1000 nt/c, parallel to the x-axis. Calculate: (a) the force, F, on the electron; (b) the acceleration of the electron along the x-axis. 2. 3 Calculate the force between the proton and the electron in the H-Atom. Assume qp-1.6 X 10.19 C, qe1.6x 1019C, 0.53 X 1010 m. 4. For a square parallel plate capacitor determine the length of one side if C = 0.5 farad, d = 1 mm = 1.0 X 10-3 m 5. Two parallel plates are separated by a distance, d 10 x 102 m. There is an E-field of 100 Nt/C between the plates: (a) the voltage between the plates; (b) the work done in moving at charge of 2 uc from one side of the field to the other. 6. A source charge, Qs 20 uc is located at the origin. Calculate (a) the E-field at r 10 X 102 m away along the x-axis; (b) the voltage at the same distance from the source charge

Answer 1

1)

(a) Line of force is an imaginary line which represents the strength and direction of a magnetic, gravitational, or electric field at any point.

(b) A conservative force is a force with the property that the total work done in moving a particle between two points is independent of the path taken.

(c) An electric potential is the amount of work needed to move a unit of positive charge from a reference point to a specific point inside the field without producing acceleration.

(d) A dielectric is an electrical insulator that can be polarized by an applied electric field.

(e) Flux is the presence of a force field in a specified physical medium, or the flow of energy through a surface.