Obj: Map E Fields using Equipotential Lines
Materials: voltmeter, grid paper, conductivity paper and Ag ink
I. Parallel Lines
1. Obtain the conductive paper with the parallel lines and a piece of grid paper.
2. Place your conductive paper on the board, then hook up the electrodes as indicated on the sketch. Set the voltmeter to 200 V DC. Label the + and - electrodes on your grid paper.
3. Apply a potential difference of 5 Volts between the two electrodes.
4. Begin mapping by using points to locate one field line of equipotential at 1.0 Volts. Using a pencil, connect the dots of this equipotential line on your grid paper before going on to another line. Continue with another equipotential line at a higher voltage (for example 1.8 Volts). The number of equipotential lines (6-8) should enable you to draw the general pattern of the electric field E over the entire grid paper.
5. Since the equipotential field lines are perpendicular to the electric field lines, draw in the electric (E) field lines using a crayon. (NOTE: lines must not cross.)
6. Based on the volts (V) and distance (d), calculate the maximum electric field (E) between your lines.
7. What force would exist on an electron placed in your E field?
8. What acceleration would occur on an electron given your calculation of force?
9. How much time would it take an electron to travel from one line to the other under these conditions?
10. What final velocity would the electron attain given the circumstances above?
Another E Field Pattern
1. Obtain another pattern of conductive paper and another grid paper. Indicate + and - electrodes. Plot out the equipotential lines as you did above, then sketch in your E field. Describe any anomalies.
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