Lesson: Uniform Electric Fields Physics • 9th Grade

In this lesson, we will learn how to determine the change in potential energy of charged objects that move parallel to uniform electric fields.

Lesson Plan

Students will be able to

recognize that parallel lines of uniformly distributed electric charges, where charges on one line are the opposite sign of the charges on the other line, result in an approximately uniform electric field between the lines,
recognize that the electric field magnitude of a uniform electric field is constant throughout the field,
relate the magnitude of a uniform electric field, , to the absolute electric potential at a point in the field at a distance d from the positively charged region from which the field lines originate, using the equation ,
recognize that the potential difference across the ends of a uniform electric field is the difference between the absolute electric potential at the end of the field at which the field lines originate and the end at which they terminate,
quantitatively model the motion of charged particles within uniform electric fields.

Lesson Worksheet

Q1:

A positively charged particle moves at a constant speed between the point and the point where it enters a uniform electric field. Assume that gravitational and drag forces on the particle are negligible.

Which of the sections of the particle’s trajectory can be consistent with the net work done on the particle being zero?

Which of the sections of the particle’s trajectory can be consistent with the net work done by the particle being zero?

Q2:

A positively charged object moves 13 cm inside and parallel to a uniform electric field with a strength of 1.28 mN/C, as shown in the diagram. What is the potential difference between the object’s initial and final positions? Answer to the nearest microvolt.

Q3:

Which of the following formulas correctly relates the electric potential difference between two points in a uniform electric field to the electric field strength, where is the electric potential difference, is the charge of a particle in the field, is the distance between the points, is the Coulomb constant, and is the electric field strength?