Online-Lab-3_Electric-Potential

.docx

School

University of Texas, Arlington *

*We aren’t endorsed by this school

Course

1442

Subject

Electrical Engineering

Date

Apr 3, 2024

Type

docx

Pages

Uploaded by GrandPowerRaccoon39

PHYS 1402 Lab 3: Electric Potential Name: _____________________ Objectives:  To review the mathematical definition of work and potential energy in a conservative force field as the sum of the product of displacement and the force-component in the direction of the displacement: W = Σ F cos θ Δs  To understand the definition of electrical potential, or voltage.  To map and examine the potential distribution in two dimensions for a variety of simple charge configurations.  To learn the relationship between electric field lines and equipotential surfaces. Marketable Skills: This course assesses the following Core Objectives. In this assignment, you will develop the following marketable skills : Critical Thinking  Analyze Issues  Anticipate problems, solutions, and consequences.  Apply knowledge to make decisions  Detect patterns/themes/underlying principles  Interpret data and synthesize information Communication  Summarize information  Use proper technical writing skills Personal Responsibility  Accept responsibility  Exhibit Time Management  Show attention to detail  Learn and grow from mistakes Empirical Quantitative  Communicate results using tables, charts, graphs  Contextualize numeric information/data  Demonstrate logical thinking  Draw inferences from data, use data to formulate conclusions  Use appropriate calculations to solve problems 1

Conservative Forces It takes work to lift an object under the influence of the Earth’s gravitational force. This increases the gravitational potential energy of the object. Lowering the object releases the gravitational potential energy that was stored when it was lifted. When you studied the gravitational force, you applied the term conservative to it because it allows the recovery of all the stored energy. You have now found experimentally that the work required to move an object under the influence of the gravitational force is path independent. This is an important property of any conservative force. Given the mathematical similarity between the Coulomb force and gravitational force laws, it should come as no surprise the experiments confirm that the Coulomb force is also conservative. Again, this means that the work needed to move a charge is independent of the path taken between the points. From the definition of work W = Σ F cos θ Δs = Σ qE cos θ Δs is the work done by the electric field E to move a small test charge q between A and B. Activity 1: Work Done on a Charge Traveling in a Uniform Electric Field 1. Suppose that a small positive test charge q is moved a distance d from point A to point B along a path that is parallel to a uniform electric field of magnitude E. Question 1: What is the work done by the field on the charge? Show your calculation. Question 2: How does the form of this equation compare to the work done on a mass m traveling a distance d parallel to the almost-uniform gravitational force near the surface of the Earth? 2. The charge q is now moved a distance d from point A to point B in a uniform electric field of magnitude E, but this time the path is perpendicular to the field lines. Question-3: What is the work done by the field on the charge? Show your calculation. 2

3. The charge q is now moved a distance d from point A to point B in a uniform electric field of magnitude E. The path lies at a 45  angle to the field lines. Question-4: What is the work done by the field on the charge? Show your calculation. Electrostatic Potential Energy and Potential The change in electrostatic potential energy is defined as the negative of the work done by the electrostatic force in moving a charge from point A to point B using any path consisting of a series of small increments of length  s . Thus, using U as the symbol for potential energy, ∆U elec = U B − U A =− ΣqE cos θ Δ s The electrical potential difference ΔV = V B − V A is defined as the charge in electrical potential energy  U elec per unit charge ΔV = ∆U elec q The electric potential difference has units of Joules/Coulomb (J/C). Since a J/C is defined as one volt , the potential difference is often referred to as voltage. Using the equation above for potential energy change, and the definition of potential difference, write the equation for the potential difference as a function of E and  s . Single Point Charge The simplest charge configuration is a single point charge. As you saw in Lab 2, a positive point charge q produces an electric field that points radially outward in all directions. The potential difference between any two points in space A and B can be found using calculus. The result is that if A is infinitely far away, and B is a finite distance r from a point charge q, then the potential difference, V, is given by the expression V = k e q r In this case, the reference point for the potential difference is at infinity, and the potential difference is simply referred to as “the potential”. Activity-2: Electric Potential of a point charge You will be using PhET simulation Charges and Fields (https://phet.colorado.edu/sims/html/charges-and-fields/latest/charges-and-fields_en.html). This 3

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version