For instance if your experiment calls for a 500 volt

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Unformatted text preview: to the power supply. 203 APPENDIX: EQUIPMENT To properly connect the CRT to the power supply: 1. Turn the power supply off. 2. Connect the power supply ports marked “AC 6.3V” (they are green; the voltage differs slightly from one supply to another, but should be clearly marked) to the ports marked “HEATER” or “FILAMENT” on the CRT (these are also green). 3. Connect the appropriate accelerating potential across the cathode and anode. For instance, if your experiment calls for a 500 volt accelerating potential, connect the cathode to the port marked “–250 V” (which may be black or white) and the anode to the port marked “+ 250 V” (which is red). This gives a total potential difference of 500 volts. 4. Turn the power supply on. 204 APPENDIX: EQUIPMENT RESISTOR CODES A resistor is a circuit element manufactured to have a constant resistance. The resistance is coded onto the side of the resistor in colored bands, where the color and position of the bands tell you what the resistance is. To read the color bands on the resistor, begin by finding the gold or silver band on one end of the resistor; this is the back of the resistor. You begin reading from the other end. Most resistors (including those you will use in lab) are coded to two significant digits. The first two color bands correspond to these two significant digits. The third color band is called the multiplier. The number coded by this band represents a power of ten which you multiply by the number from the first two bands to get the total resistance. The fourth color band tells you the tolerance, or error bounds for the coded resistance: gold means ±5% tolerance, silver means ±10% tolerance and no fourth band means ±20%. Some resistors have a fifth color band, which represents the reliability of the resistor, and can just be ignored for the purposes of these labs. Examples: R 10 102 20% R 56 10 4 5% 205 Color Number Black 0 Brown 1 Red 2 Orange 3 Yellow 4 Green 5 Blue 6 Violet 7 Gray 8 White 9 9 APPENDIX: EQUIPMENT POWER SUPPLIES The 18volt 5 amp power supply is an allpurpose power supply for the production of constant currents and voltages. At the top is the main display that reads either current in Amperes or voltage in Volts. There is a switch there that allows you to switch between them. The current and voltage controls are located in the middle. In between the constant current and constant voltage knobs is a switch that allows you to toggle from high currents to low currents. It is highly recommended that you use only the low current mode. This power supply normally operates in the constant voltage mode. As such, you can only change the voltages by using the constant voltage knobs. In the event that too much is being pulled from the power supply (as in a short), it will automatically switch to the constant current mode, where the amount of current flowing is greatly reduced. This is a signal that something is amiss with your circuit. There is a mater-slave switch on the back of the power supply. This should always be set to master for the DMM to function properly. If you experience any problems, this is the first place to check. 206 APPENDIX: EQUIPMENT THE MAGNETIC FIELD SENSOR (HALL PROBE) To measure magnetic field strength, you will need a measurement probe (the magnetic field sensor) that connects to a computer through the Vernier sensorDAQ lab interface.. The tip of the measurement probe is embedded with a Hall Effect transducer chip (shown above as the white dot on the end of the probe). The chip produces a voltage that is linear with the magnetic field. The maximum output of the chip occurs when the plane of the white dot on the sensor is perpendicular to the direction of the magnetic field, as shown below: The sensorDAQ allows the computer to communicate with the probe. In order to measure magnetic fields, the wire leading out of the probe must be plugged into the port labeled "CH 1". The Range switch on the side of the probe is to allow you to measure a greater range of magnetic field strengths. Each setting represents the maximum field strength that the probe can measure: either ±6.4mT or ±0.3mT. When measuring stronger magnetic fields, you should use the 6.4mT setting, but for fields weaker than 0.3mT the lower setting will give you a more accurate reading. 207 APPENDIX: EQUIPMENT The measurement probes have swiveling tips to allow for more convenient data collection. Note: that these tips are only meant to swivel in one direction. They will break of they are bent in the other direction, and they are very fragile, so it does not take much to do this. Please be very careful as these are costly to replace. 208 APPENDIX: EQUIPMENT RE-MAGNETIZING A BAR MAGNET The magnetizer should be used if you have a bad bar magnet that isn’t a simple dipole, polarity doesn’t match the labels, or the magnet is too weak. Important to know is that the magnetizer is poorly labeled. The N and S do not indicate the end of the magnet that goes into the magnetizer! We believe the company is trying to imply th...
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This document was uploaded on 02/23/2014 for the course MANAGMENT 2201 at University of Michigan.

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