INTRODUCTION The concept of electric field was introduced by Michael Faraday. The electrical field force acts between two charges, in the same way that the gravitational field force acts between two masses . In physics, an electric field is the region of space surrounding electrically charged particles and timevarying magnetic fields. The electric field is a vector field with SI units of newtons per coulomb (NC−1) or, equivalently, volts per metre (V m−1). The direction of the electric field is always directed in the direction that a positive test charge would be pushed or pulled if placed in the space surrounding the source charge. A useful means of visually representing the vector nature of an electric field is through the use of electric field lines of force. The electric field from a positive charge points away from the charge; the electric field from a negative charge points toward the charge. Like the electric force, the electric field E is a vector. If the electric field at a particular point is known, the force a charge q experiences when it is placed at that point is given by : F = qE. If q is positive, the force is in the same direction as the field; if q is negative, the force is in the opposite direction as the field. Also, when the electric field, E is stronger, then the force experienced is larger.
A uniform field is one in which the electric field is constant at every point. It can be approximated by placing two conducting plates parallel to each other and maintaining a voltage (potential difference) between them. The equation for the magnitude of the electric field E is where V is the potential difference between the plates and d is the distance separating the plates. A high voltage means that each individual charge is experiencing a large force. A low voltage
means that each individual charge is experiencing a small force. When same charges are put close together, there will be high voltage because it has a high potential energy. The larger the distance is, the smaller the force and voltage are.
In regions where the electric field lines are equally spaced, there is the same number of lines per unit area everywhere, and the electric field has the same strength at all points. For example, the diagram above shows that the field lines between the plates of a parallel plate capacitor are parallel and equally spaced, except near the edges where the bulge outward. The equally spaced, parallel lines indicate that the electric field has the same magnitude and direction at all points in the central region of the capacitor. In this experiment, a software called Efield is used to investigate the electric potential, electric field lines, and equipotential lines by using simulation. Also, the electric force will be observed through real time interaction of charges.
PURPOSE OF INVESTIGATION To investigate the electric field strength and electrical potential within a uniform electric field. APPARATUS Computer running the program ‘Efield’ downloaded from website www.physicslab.co.uk. PROCEDURE The program was installed and opened to start an experiment. ‘Electric field strength’ was selected and the electric field lines was plotted by clicking the mouse in the field. The trend of the graph of electric field strength E against d was observed. In the same page, ‘electrical potential’ was
selected and measured at different positions between the plates. At the graph of V against d, the trend of the potential against distance from the bottom was observed. The results were printed out and examined. RESULTS
Diagram 1 The electric field between charged parallel plates
Diagram 2 The electrical potential against distance from bottom plate
ANALYSIS From diagram 1, we can see that the electric field strength is same at any points which is 200V/m. Diagram 1 shows that shows that the electric field line are equally spaced and there are same number of lines per unit area everywhere. From the graph of electric field strength against the distance, the field strength is constant in the region between the plates. In diagram 2, the line that crossed the elecric field is the potential difference (V). From the result, the potential difference varies according to the distance from bottom plate and the graph showed the relationship between potential difference with distance from bottom plate is directly proportional. The further the distance from the bottom plate, the bigger the potential difference. DISCUSSION In this experiment, it was confirmed that electric field strength between two plates is uniform at any point. From the equation
, the value obtained for the electric field strength was
approximately same which is 190 Vm-1. Therefore, in this experimant, the magnitude of the uniform electric field between the two plates would be approximately 190 Vm-1. Also, from the graph obtained in diagarm 2, it showed the relationship between V against d is directly proportional. It suited the equation
, which rearranged to E = V.d , when the distance is
increased, the potential difference also increased and the gradien of the graph is the uniform electric field strength. CONCLUSION From this simple experiment, it can be concluded that electric field strength between two plates are uniform at any points. This theory can be investigated using the formula the distance between two plates, the larger the potential difference.
. The further
