Lab3 lab report Electric Field Mapping PDF

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Lab3 lab report Electric Field Mapping...

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Queens College of The City University of New York Department of Physics Physics 122.1: General Physics II Lab 3: Electric Field Mapping

By: Lamia Hauter & Hallah Almaroosh

ABSTRACT: 1. What is an electric field? It is the force per unit charge exerted on a test charge ,q, that moves into the space of the field at any point. This force is represented by imaginary lines that provide a graphical representation of the electric field. 2. Do they really exist? The electric field lines are only imaginary smooth curves so they don’t really exist but the field exists to demonstrate the electric force around the object. 3. How do we represent an electric field? Field lines used to represent the electric field vector for a charge. T  he lines begin on positive test charge and radiate away from them toward negative charge sphere, where they terminate 4. How are electric potential and electric field related? electric field lines are perpendicular to equipotential lines. They are related as; E = V /d. The strength of the electric field is directly proportional to the closeness of electric field lines. The closer the electric field lines are, the stronger the electric field will be.

PROCEDURE 1: Figure 1.

Image 1. Sketch of the electric field of 2 charges (positive and negative)

PROCEDURE 2: Figure 2. Two of each charge (positive and negative) stacked with 10 equipotentials

Figure 3. Addition of three more of each charge (total of 5 of each charge) with 10 equipotentials

Image 2. Sketch of a set of parallel plates and the field between them

PROCEDURE 3: Figure 4. A series of 8 equipotential lines with the electric fields

ANALYSIS: In procedure 1 for the single charge, the equipotential lines are circles around the charge. The electric field is perpendicular to the equipotential lines. The larger radius equipotential lines have, the lower the potential. When we have two charges (positive and negative), the equipotential lines are flattened between the charges. In addition, the lines in the area between the positive and the negative charges are denser and closer to one another compared to the lines that are widely separated in the right side of the negative charge and the left side of the positive charge (Figure1). In procedure 2, it was observed that when we have many charges, the potential lines become parallel between the charges. This is the capacitor where the equipotential lines are parallel. Two equipotential lines cannot cross each other, because at the point of intersection, there will be two values of potential at the same point, which is not possible. Similarly, electric fields can not cross. In procedure 3, the electric field is perpendicular to the equipotential lines. At the conductor surface, the electric field is perpendicular to the surface while the equipotential lines are tangent to the surface. At the insulator surface, the electric field is tangent to the surface while the equipotential lines are perpendicular to the insulator surface. In an electric field, free charges appear at the surface of conductors and insulators. When you have metallic conductors, the free charges re-arrange on the conductor surface until there is no potential difference inside the conductors (no electric field inside the conductor). Thus, the potential lines are tangent to the conductor surface. In an electric field, the nonconductors have a

bound charge. This bound charge creates a polarization vector inside the insulator that opposes the electric field. Thus, inside the insulator the electric field is lower.

CONCLUSION: In this lab, the electric field of the charges was studied. An electric field is a vector quality that has both direction and magnitude. It exists at every point in a space and indicates the force acts on a positive test charge ,q, that moves into the space of the field at any point. The charge test is always positive and when the source of the charge (sphere) is negative an attraction will take place as shown in the previous procedures. The electric field is represented through imaginary lines that begin on positive test charge and point toward the negative charge. The more and the denser the field lines are, the stronger the electric field. The relationship between the electric field lines and equipotential can be represented by E = V /d . Equipotential indicates that every point in a region in a space has a constant electric potential connected by a line that is perpendicular to the electric field lines. Two equipotential lines cannot cross each other, because at the point of intersection, there will be two values of potential at the same point, which is not possible. Similarly, electric fields can not cross. For different charge geometrics, we have found the shape of the equipotential lines and the electric field. When you have one charge, the equipotential lines are circles around that charge whereas when you have two charges, the equipotential lines tend to flatten between the charges. The interaction between the electric field, the conductors, and the insulators were observed. While inside the conductors, the electric field is zero and the electric potential is constant. Inside the insulator the electric field is lowered because of the polarization vector....