# Physics Lab Report

Essay by PaperNerd ContributorHigh School, 12th grade February 2002

In this lab our group was to find how the deflection of the electron beam varies when passing through an electric field perpendicular to the velocity of the electron beam. It seemed fairly confusing at first, but as we started working on the equation, the ideas involved were easily understandable. The only confusing part was defining the equation that we should use to evaluate the results.

Equipment: 1 Cathode Ray Tube (with deflection plates and a graph on the end) 1 power supply Multiple connectors Our group hooked up the cathode Ray Tube to the power supply with the connectors, and turned it on. The first time we did this it didn't work, so we checked with the TA and found that we were supplying too many volts to the CRT. We were using 500V instead of 250V. We fixed this problem and a green dot appeared on the screen at the end of the CRT.

Because gravity and magnetic fields in the room were acting on the CRT, we had to turn it around to find a plane in which the green dot lined up in the center of the graph. We used this as our point of origin. We then proceeded to measure the distance the dot traveled resulting from several different voltages applied to the deflection plates. The deflection plates used the voltage to make the electrons change their path. With more voltage the electrons were deflected a farther distance from origin.

I was unable to come up with an equation that would produce the amount of total deflection. We worked on it for a while and our attempts proved inadequate. Our TA gave us the equation: Total Deflection = E L (D + L/2) 2 Vacc These are your readings from the chart on the end...