# Introduction

Electric field is the force per unit charge and the direction of the force is taken to be the direction of the force it would exert on positive charge. It radiates outward form a positive point charge and inward from an inward point charge.

Electric fields do exist but it’s an invisible entity that exists around an area of a charged particle called a source charge. The electric field and electrical potential are related with the fact that electrical potential describes the field action on an object. For a uniform field, the relationship between electric field (E), potential difference between points A and B (Δ), and distance between points A and B (d) is and its units is the inverse of coulomb.

# Experiment objective

The main objective of this experiment is to map the electric field in various situations using the simulation software PHET.

# procedure ONE

• Set the PHET simulation charges and fields.
• Clicked the reset swirly option. Turned off the electric field and the grid
• Dragged 1 positive, red and 1 negative blue charge from the bottom box and placed them on the main window 3 major grid lines the thicker ones a part. Dragged the equipotential tool onto the window and maneuvered the crosshairs to a point between the charges and the 1 minor gridline away from positive charge. Clicked the pencil icon.
• Moved 1 minor grid line towards the negative charge and clicked on pencil icon again.
• Continued doing this till I reached the pencil icon.
• On bottom right of screen placed a 3 bar menu, opened it and took screen shot below.

# PROceedure two

• Clicked the reset swirly, turned off the electric field an turned on the grid.
• Stacked two of each charge and one major grid line apart.
• Created ten equipotential in the space around the charges.
• Observed the shapes and line density in space around the charges
• Added more of each charge above others.
• Repeated the pacing of ten equipotential.
• Added five more charges above the others.
• Observed the shape and line density in the space around the charges.
• Took a screen short

# Procedure three

• Closed the PHET simulator.
• Printed the image which data collected with overbeck apparatus

# Procedure one

The equipotential behave like concentric spherical shells and the distance between the shells keep changing with the influence of electric field between charges. The potential of a point charge is the same on imaginary sphere and thus has the same value at any point that is from the charge. Since electric fields lines always points radially away from charge they will be perpendicular to the equipotential lines. The sketch of electric field line is as shown below.

# Procedure two

The equipotential lines are spherical and reduce as the distance of field lines decreases. The equipotential density is more constricted at the grids between the negative and positive charges.

# Procedure three

The overbeck apparatus captured image.

Difference between conductors and non-conductors

Conductors have electrons moving freely from atom to atom whenever a potential is applied across it therefore easy charge movement whereas nonconductors have their electrons fixed due to atomic level forces and hence no easy charge transfer.

What can electrons in a conductor that electrons in non-conductor cant?

Move freely from atom to atom

How electrons do responds Coulomb force

Coulomb force is the interaction attraction or repulsion of particles or objects because of their electric charges. Conductors contain free charges that move easily. When excess charge is placed on a conductor or the conductor is put into a static electric field, charges in the conductor quickly respond to reach a steady state called electrostatic equilibrium. The free charges move until the field is perpendicular to the conductor’s surface. There can be no component of the field parallel to the surface in electrostatic equilibrium, since, if there were, it would produce further movement of charge. Free charges can be either positive or negative and are, in fact, negative in metals. The motion of a positive charge is equivalent to the motion of a negative charge in the opposite direction.

Electric field in conductors.

A conductor placed in an electric field will be polarized. Figure 2 shows the result of placing a neutral conductor in an originally uniform electric field. The field becomes stronger near the conductor but entirely disappears inside it.

Figure 2. This illustration shows a spherical conductor in static equilibrium with an originally uniform electric field. Free charges move within the conductor, polarizing it, until the electric field lines are perpendicular to the surface. The field lines end on excess negative charge on one section of the surface and begin again on excess positive charge on the opposite side. No electric field exists inside the conductor, since free charges in the conductor would continue moving in response to any field until it was neutralized.

ELECTRIC FIELD LAB DATA SHEET

Is it possible for electric field lines to cross each other?

This is because at any point, if electric field lines cross each other it means at that point there are two directions of electric field, which is impossible.

Electric field of same charges particles.

For both which are negative charges the direction of the electric would been inwards to the center of the charges.

Relationship of electric field strength with to equipotential lines.

Equipotential lines are like contour lines on a map which trace lines of equal altitude. In this case the “altitude” is electric potential. Equipotential lines are always perpendicular to the electric field. Movement along an equipotential surface requires no work because such movement is always perpendicular to the electric field.

Electric field inside a conductor and insulator

A conductor is a material in which charges are free to move over macroscopic distance, they can leave their nuclei and move around the material. An insulator has their charges fixed. In an insulator the charge distribution in an atom may change, but the charges do not leave their nuclei. When we consider electrostatics, the case where charges are not moving. There can be no electric field inside a conductor. If there were, it would exert a force on the charges causing them to move. They would adjust until there was no field, there can be no net charge at any point inside a conductor.