Mapa Institute of Technology

Department of Physics

Experiment 305

ELECTRIC FIELDS AND

EQUIPOTENTIAL LINES

Name: Saccuan, April Jem H.

Program/Year: CpE/2

Course Code/Section: PHY12L/A1

Student No.: 2012100116

Group No.: 5 Seat No.: 502

Date of Performance: February 11, 2014

Date of Submission: February 18, 2014

Prof. Bobby Manlapig

Instructor

GRADE

QUESTIONS AND PROBLEMS

1. Is it possible for equipotential lines to intersect each other? Justify your answer.

Yes, it is possible for equipotential lines to intersect each other if and only if the two

charges have the same charge (positive-positive or negative-negative), same value of the potential

as each other, and they are emerging from or converging to the same singularity.

2. From the electric field pattern that you obtained, what is the relationship between the spacing of

the field lines and the electric field magnitude?

It is not quite seen in the pattern drawn but more likely, the closer the field lines are to

each other, the stronger the electric field magnitude will be. By the equation and graph it is said

that the electric force is also inversely proportional to the square of the distance of charges with

each other.

3. If an electron is at the midpoint of the line connecting two equal but opposite charges in a direction

perpendicular to this line, does the charge experience zero electric force due to the two charges?

If not is there a point along the line connecting the charges where the electron will experience a

zero electric force? Where is this point located?

The charge does not experience zero electric force because for the point midway between

the forces acting on the electron are in same line but also in the same direction so they will add.

The force will be zero only at infinity because between the charge forces will add but beyond

forces will oppose but they would never be equal in magnitude.

4. Sketch the electric field between two positive charges of equal magnitude.

MAPUA INSTITUTE OF TECHNOLOGY DEPARTMENT OF PHYSICS

EXPERIMENT 305 : ELECTRIC FIELDS AND EQUIPOTENTIAL LINES

Name Saccuan, April Jem H. Group No. 5

Program/Year CpE/2 Seat No. 502

Subject/Section PHY12L/A1 Date 02/11/14

DATA and OBSERVATIONS

A. Dipoles of Unlike Charges

Multimeter

Reading

Coordinates, (x,y)

3.23 Volts

9 0

9.5 1

10 2

12 3

3.27 Volts

8 0

10 3

11 3.5

12 4

3.32 Volts

7 0

9 4

10 5

12 5.5

3.38 Volts

6 0

7 3

9 5.5

12 7

3.46 Volts

5 0

7 6

9 8

12 9

MAPUA INSTITUTE OF TECHNOLOGY DEPARTMENT OF PHYSICS

EXPERIMENT 305 : ELECTRIC FIELDS AND EQUIPOTENTIAL LINES

Name Saccuan, April Jem H. Group No. 5

Program/Year CpE/2 Seat No. 502

Subject/Section PHY12L/A1 Date 02/11/14

DATA and OBSERVATIONS

B. Point Source and Guard Ring

Multimeter

Reading

Coordinates, (x, y)

6.43 Volts

6 0

3 5

5 3

0 6

6.36 Volts

5 0

4 2

2 4

0 5

6.29 Volts

4 0

3 2

2 3

0 4

6.23 Volts

3 0

2 2

1 2.5

0 3

6.21 Volts

2 0

1.5 1

1 1.5

0 2

Approved by:

Prof. Bobby Manlapig

02/11/14

instructor date

ANALYSIS

1. Why is the voltage reading along an equipotential line zero?

The digital voltmeter measures the potential difference between the point on

the paper where the probe is held and the conductor connected to the other lead of

the voltmeter. Voltage is a potential difference. Since we read along an equipotential

line or a line with equal potential, then getting its difference will yield no difference,

as well as, voltage.

2. At what point is the voltage reading greatest? What is the significance of this?

The greatest voltage reading would be if the difference between the lines of

equipotential is greatest. A positive test charge would be at high electric potential when

held close to a positive source charge. Hence, decreasing the distance from the point

source, the voltage increases. Knowing this relationship would be of great reminder

that when a test charge is being made which is very far from the point source, a high

voltage was being made and high voltages should be taken cautioned of.

3. Describe the electric field inside the guard ring.

Plotting the points with equal potential on a guard ring and using origin as the

point source, circular paths are produced. This means that as the circular silver lining

was made, the electric lines are trapped inside the ring because silver is a conductor

and thus conduct electricity. The same in the first experiment, conversely, increasing

the distance from the point source the voltage decreases.

CONCLUSION

In this experiment, we studied the nature of electric fields by mapping the equipotential lines and then drawing in the electric lines of force or electric field lines

which are always perpendicular to each other. An electric field is an area where electric force is present while equipotential lines are lines with equal potential.

For experiment 1, plotting the points with equal potentials produce a parabolic

figure and then the field lines are drawn intersecting the potential lines perpendicularly. For experiment 2, we produce circular potential lines and so the

electric field lines are all radii of the guard circle and the other circles since we produce concentric potential lines.

Performing this experiment, it is concluded that equipotential lines are

proportional in strength with respect to the distances from the point source. Finally, voltage is indirectly proportional to the distance from the point source.