Experiment No. 1 Equipotential and Electric Fields I . OBJECTIVES Describe clearly the concept of a force field. Explain lines of force and the associated physical interpretations. " Distinguish between lines of force and equipotential, and describe their relationships to work. II THEORY III . EQUIPMENT Field mapping board and probes Conducting sheets with grids Conducting paint Connecting wires DC power supply (10V) Voltmeter IV PROCEDURE Electric Field 1. Draw the electric dipole configuration on a sheet of graph paper to the same scale and coordinates as those of the painted dipole on the imprinted grid on the conducting sheet. Then place the dipole conducting sheet on the board, and set the contact terminals firmly on the painted electrode connections. 2. For the voltmeter, the field probe should have two contacts mounted about 2 cm apart. Connect the voltage source (10-V dc) to the board terminals. Position the negative (-) contact of the field probe near the negative electrode. Using the negative probe point as a pivot, rotate the positive (+) contact around the fixed negative contact until the position with the maximum meter reading is found. Record the positions of the probe contacts on the graph- paper map.3.Using the second probe point as a new negative probe point, rep at the procedure to determin another point of maximum meter reading, and record. Continue this procedure until the positive electrode is approached. DraW' a smooth curve through these points on the graphpaper map. Then, starting again at a new position near the negative electrode, repeat these procedures for another field line. Trace out four to six field lines in this manner. Do not forget to indicate the field direction on the lines. 4.Place the negative probe near the center of the field region, and rotate the positive contact until a position is found that gives a zerometer reading. Record several 0: these points on the graph paper with a symbol different from that used for the field lines. Check the zero on the voltmeter frequently, particularly when changing scales. Use the second point as a new pivot point, as before, and determine a series of null (zero) points. Draw a dashedline curve through these eguipotential points. Determine three to five equipotential lines in this manner. 5.Repeat this procedure for the parallel linear (plate) electrode configuration. Be sure to investigate the regions around the ends of the plate electrodes. Magnetic Field 1. Covering the magnets with sheets of paper or transparency material, sprinkle iron filings to obtain an iron filing pattern for each of the arrangements shown in Figure ELI! Q (a) {2:} [D (D) 5:: (c) For the bar magnet arrangements, the magnets should be separated by several centimeters, depending on the pole strengths of the magnets. Experiment with this distance so that there is enough space between the ends 0: the magnets to get a good pattern. 2.Sketch the observed magnetic field patterns on Figure. After the patterns have been sketched, collect the iron filings on a piece of paper and return them to the filing container. 3.Place the magnets for each arrangement on a piece of graph paper or regular paper. Draw an outline of the magnets for each arrangement on the paper, and label the poles N and S. Using a small compass, trace out (marking on the paper) the magnetic field lines as smooth curves. Draw enough field lines so that the pattern of the magnetic field can be clearly seen. Do not forget to indicate the field direction on the lines. 4. Draw dashed-line curves perpendicular to the field lines. V. DATA AND RESULTS Attach graphs VI . CONCLUSIONS VII . QUESTIONS 1. Why are the measured equipotential lines instead of surfaces for this laboratory? 2. Directions of the fields are indicated on field lines. Why are no directions indicated on equipotential lines? 3. Comment on the electric field of the parallel plates (a) between the plates, and (b) near the edges of the plates. 4. Why it is important to center the electrodes on the resistance paper for this experiment? 5. Explain how a gravitational field might be mapped. Sketch the gravitational field for two-point masses a short distance apart. References : 1. https : / /www. youtube . com/watch?v=WcSSWN4Tnoo 2. https ://www. youtube . com/watch?v=IJgzVaTPEow 3. https :/ /phet . colorado . edu/sims/html/charges-and- fields/ latest/charges-and-fields en . html