As I mentioned during class, this week is NOT a full report. This means that you just need to fill in the table at the end of the assignment, the few questions below the table, the calculations for the resistance of the Shunt Wire, but also the length of that wire!
Also, you must include all the pages and calculations for the Take-home portion of the lab and answer all the questions related to that portion as well.
Microsoft Word - Lab 4_316_2021.docx Lab Section # 4 Circuit Diagrams & Ammeter-Voltmeter Part I 4A-Circuit Diagrams Here are some common circuit symbols. In the lab this semester, you will only need to deal with about one fifth of these. Don't panic if they look strange or you don't know what a resistor or a capacitor is B you are in the right place. Part 1 (take Home lab): Note: You will need these wires, battery holder, batteries, light bulbs for the next lab!!!! A) Resistors in parallel and series Grocery List Breadboard multimeter 3 resistors hook up wires battery, 3 V attached with your set or two 1.5V batteries You may need cardboard box, aluminum foil, and a potato Put two AA batteries together. You may build a battery holder or tape batteries together (though it will be hard) or use device with equipment for 3 V that comes with breadboard. (If you need to build a battery holder, there is movie on youtube at the beginning) https://www.youtube.com/watch?v=_GI1gWBXNrw&t=5s Check the voltage of your battery ________________ 1)Measuring resistance You may safely measure the resistance of your own body by holding one probe tip with the fingers of one hand, and the other probe tip with the fingers of the other hand. You have a high resistance across your body, Note: be very careful with the probes, as they are often sharpened to a needle-point. Hold the probe tips along their length, not at the very point! You may need to adjust the meter range again after measuring the 10 kΩ resistor, as your body resistance tends to be greater than 10,000 ohms hand-to-hand. Try wetting your fingers with water and re-measuring resistance with the meter. What impact does this have on the indication? Try wetting your fingers with saltwater prepared using the glass of water and table salt, and re-measuring resistance. What impact does this have on your body's resistance as measured by the meter? Resistance is the measure of friction to electron flow through an object. The less resistance there is between two points, the harder it is for electrons to move (flow) between those two points. Given that electric shock is caused by a large flow of electrons through a person's body, and increased body resistance acts as a safeguard by making it more difficult for electrons to flow through us, what can we ascertain about electrical safety from the resistance readings obtained with wet fingers? Does water increase or decrease shock hazard to people? Measure resistances of different objects as well as try some vegetables or fruits. I used a lemon? You may use anything else like potato. Resistance of different objects You also have to measure three resistors object Resistance Comments Human body Human body (wet) Aluminum foil Resistor 1 Resistor 2 Resistor 3 lemon Extra pts: built a potato battery, show set up picture and explain physics behind it. You now can measure voltage and current of your circuit. Put the smallest resistor in the breadboard and connect to the battery Measure voltage without isolating the components. Voltage is the easiest thing to measure with a multimeter. To measure a current you must put the meter in the circuit, which means cutting a wire to insert the meter. Measuring voltage is as easy as placing the meter probes at two points and reading the meter that indicates the voltage difference between the two points. 2) Measuring voltage and current Create similar circuit: Record Voltage ___________________ Create this circuit: Record current____________ Calculate your resistance____________ Compare it with your measured value of the resistor________________ 3) Series circuit. Create a series circuit like this with your resistors Make a set up as shown in picture Make a picture of your set up and add it with your lab report Measure voltage drop around any of the resistors ____________ Measure current around any resistor_______________ Calculate resistance based on Ohms Law ____________ The % difference between measured and calculated one _________ Measure total resistance like this setup: Total resistance measured __________ Total resistance calculated __________ The % difference___________ 4) Parallel circuit Set up a parallel circuit Take a picture of your set up and add it to your lab report Check voltage drop around any resistor____ Current around any resistor____________ Calculate resistance for that resistor based on Ohms law _______ The % difference_________ Measure total resistance of the circuit________ Calculate total resistance of the circuit___________ The % difference______________ You are next suppose to measure your total resistance similar to this: Part II (STREAM LAB) Equipment that will be used: Galvanometer Decade Box Resistors; (In your labs it will be used for R0 and R1 ) C. Single Pole Knife Switch (S); shown here the switch is in the Closed position, meaning that the circuit loop in which this inserted will be completed, so electricity (electrical current) will flow. 4B-Ammeters and Voltmeters Purpose: To study the physical principles involved in the design of DC voltmeters and DC ammeters. Apparatus: A DC galvanometer, resistance boxes, a power supply, copper wire, a laboratory digital voltmeter, potentiometer. Theory: The galvanometer is the heart of a DC voltmeter and DC ammeter. The galvanometer is in fact a sensitive ammeter, i.e., it is an instrument which will measure a current in the range of microamperes. The purpose of this experiment is to show how much an instrument can be used to construct an ammeter and voltmeter. The DC galvanometer, as shown on the right, consists of a coil of wire placed in the magnetic field of a permanent magnet. When a current flows through this coil, the magnetic field produced will tend to align itself with the magnetic field of the permanent magnet. For a given coil and a given permanent magnet the torque produced will depend on the current in the coil and on the angle between the magnetic field of the permanent magnet and the plane of the coil. The manufacturers of galvanometers usually try to eliminate the angle factor so that the torque will depend only on the current. A measurement of the torque will then constitute a measurement of current. The measurement of torque is accomplished by arranging for a counter torque to be developed as the coil rotates. One of the ways of producing his counter torque is to attach a small coil spring to the axis of the current coil. As the axis rotates the coil spring tries to prevent this rotation. The counter torque is designed to be proportional to the angle the axis has been rotated. In this way, the angle through which the coil rotates measures the current in the galvanometer. The angle is read on a scale marked off in amps, or ma. One needs to know some of the characteristics of a galvanometer before it is possible to proceed successfully in the construction of voltmeters and ammeters. In particular, one needs to know the resistance of the galvanometer and the maximum current that is allowable for the galvanometer. A third characteristic which is usually assumed but which is important is that the deflection is directly proportional to the current passing through the galvanometer. If high precision were required then this characteristic would need to be checked. To determine the galvanometer resistance we will use Half deflection method. The galvanometer is connected in series with a high resistance so that the current does not exceed the maximum current. By connecting a known resistance in parallel with the galvanometer the current through the galvanometer will