Lab # 9: Charge to Mass Ratio of the Electron PROCEDURE - SET UP B: 1. Set up the apparatus as shown on the diagram on the next page. Check for the following: Make sure all power supplies are turned OFF. Turn the control knob on the "Green" power to the zero position (fully counterclockwise). This is the accelerating voltage. Call your teacher to have your circuit checked. Your teacher will give you a power cord.Lab # 9: Charge to Mass Ratio of the Electron e/m experimental apparatus Circuit-test PSC-520 Filament Accelerating Deflection 6.3 V Voltage Plates 0-200V DC 0-50V DC Voltage OOQ O Current Fuse 250V T1A Upper Lower Switching mode power supply voltage 1-20VDC sigmatron Switching output current 120 0-5ADC 6.3 V 2A max O+ Power Supply (Heater) Power Supply (Helmholtz coils) Controls accelerating voltage of the electron gun SET UP BPROCEDURE - SET UP B: Tubes are EXPENSIVE! $$$$$$$$$$ Turn everything off when you are done making measurements. Leave everything connected while you do your calculations, so that you can measure again if something went wrong. Never exceed 9V on the power supply (Helmholtz coils). Never exceed 2A current. 2. Turn on the "Green" power supply. The filament inside the tube should begin to glow red: the 6.3V supply is heating it up, releasing electrons. 3. On that same green power supply, slowly turn the voltage adjust knob for the accelerating voltage. Keep turning it up until a clear beam emerges from the tube. The required voltage is about 100V. 4. Turn on the Helmholtz coils power supply and make sure the switch is open (it is indicated on the screen: _/ _ symbol). Give each knob (voltage and current) a few counterclockwise spins so that they are near zero values when you eventually close the switch. Keeping the switch open, increase the voltage until it is about 9V. This sets the limit value. 5. Close the switch by pressing the switching output button (from _/ _symbol to _). Slowly increase the current until you see the beam begin to curve. A full circle should be produced when the current is approximately 0.9A (the voltage will change automatically vary but will remain below the preset value). Note that different apparatuses will have different set points, thus the current where you get a full circle will vary from group to group. Watch the reading on the screen and take care that the current does not exceed 2A and the voltage does not exceed 9V. 6. Carefully measure the radius of the electron beam: Look through the tube such that you can see both a big circle (the beam itself) and a smaller circle (its reflection in the mirror). a) Vertical adjustment: Adjust your head up and down until the smaller circle is vertically centered inside the larger circle. b) Horizontal adjustment: Move your head to the left until the left edge of the smaller circle touches the left edge of the big circle. Move the marker on the scale until it is6. Carefully measure the radius of the electron beam: Look through the tube such that you can see both a big circle (the beam itself) and a smaller circle (its reflection in the mirror). a) Vertical adjustment: Adjust your head up and down until the smaller circle is vertically centered inside the larger circle. b) Horizontal adjustment: Move your head to the left until the left edge of the smaller circle touches the left edge of the big circle. Move the marker on the scale until it is aligned with the point of overlap. Record the reading. Repeat on the right-hand side and take a second reading. You may need to readjust your vertical alignment before Physics 203-NYB-05 Electricity & Magnetism Lab # 9: Charge to Mass Ratio of the Electron taking your readings. The radius will be the average of the two readings. (This procedure is required because the zero of the mirrored scale is slightly shifted from the center of the beam track.) 7. Set the value of current: / - 1.2 A, and vary accelerating voltages from 100 V to 125 V 8. Change the value of the magnetic field B by setting the current through the coils to (about) 1.3A. Repeat the measurements for accelerating voltage varying from 125 V to 150 V. 9. Change the value of the magnetic field B by setting the current through the coils to (about) 1.6A. Repeat the measurements for accelerating voltage varying from 150 V to 200 V.Lab 9 e/m ratio report format No cover page . Theory [3 pts] Do ONLY the following items. For each, precede each mathematical step with words of explanation. 1. Starting with F = quxB Show how it leads to an expression for the radius of curvature for a charged particle: qB 2. Using the above expression, show how we obtain the following when a charged particle is accelerated from rest across a potential difference of V and then directed into a magnetic field B: ro 2V m B272 Data and Results ( subscripts and superscripts must be displayed correctly, not eg "10 2" or "E-2" ) remember to use correct formatting for labels of data table columns and graph axes! Obtain at least 4 data points for each of the 3 values of current. Fill in the information requested in Data and Results Table from the lab manual ( or reproduce your own version ). For each value of B, plot r vs. V/B2 all 3 graphs MUST be on the same pageData and Results "10^2" or "E-2" ) ( subscripts and superscripts must be displayed correctly, not eg ** remember to use correct formatting for labels of data table columns and graph axes! Obtain at least 4 data points for each of the 3 values of current. Fill in the information requested in Data and Results Table from the lab manual ( or reproduce your own version ). For each value of B, plot r vs. V/B2 all 3 graphs MUST be on the same page state the value of B in the title use a "scatter plot"; scales axes to avoid "dead space". do not connect the dots, but do superimpose a line of best linear fit ensure that the equation for the fit is displayed Data Table 2: theoretical value of e/m ; final values of e/m for each value of B; % deviation. ( Note that e/m is related to the slope but is not equal to it. ) Sample Calculations ( follow correct format ) One of each type including calculation of e/m from the slope of a graph Conclusions NoneTable.2 Percent deviation B value (T) theoretical value of final values of e/m (%) e/m for each value of BTable. 1 = 130 tums I(A B(T) Vac -(V radius(m) 299 0.0350 318 0.0040 1.430 279 0.0300 0.0375 299 10.004 1.601 330 0.0374 338 0.0420 345 0.0450 248 0.0326 264 10.0375