Experiment I
Simple Voltage and Current Measurement
Objective
The objective of this experiment was to measure the Voltage and Current. Upon completion of this experiment I was able to:
1) Set the DC power supply to a specific voltage.
2) Properly connect the voltmeter to measure voltage.
3) Measure current with the ammeter.
4) Measure resistance with the ohmmeter.
5) Determine the accuracy of a given meter reading.
Theory
The theory required for this experiment was an understanding of Ohm’s Law. Ohm’s Law is the algebraic relationship between voltage and current for a resistor. Resistance is the capacity of materials to impede the flow of current or electric charge. Ohm’s Law expresses the voltage as a function of the current. It was also necessary that the concept of measurement accuracy be understood. This is discussed below.
Accuracy is of primary importance in an experimental work. The tolerance quoted by the meter manufacturer allows us to calculate the accuracy of any reading taken with that particular meter. For example, assume that the dc voltage scale on a particular multimeter is rated at ± 3% of full scale. This means that a reading on the 10V scale is accurate to (± 0.03%)(10) = ± 0.3V. Thus, a reading of 9V on the10V scale indicates a true voltage, which lies between 8.7 and 9.3 V. A reading of 1V on the scale would indicate a true voltage between 0.7 and 1.3 V. At this point, the error is ± 30%! Any reading less than 10% of full scale should be viewed with suspicion since most meters are very inaccurate n this range.
Circuit Diagrams
For this experiment we used a Power supply source, voltmeter/ammeter/ohmmeter.
Fig 1.1 Power Supply and voltmeter in parallel
Power Supply Voltmeter
-
Fig 1.2 Simple voltage measurement circuit.
a a
b a b a a d c c d
c d
Fig 1.3 Simple current measurement circuit
Power Supply
(Be sure current I control is at maximum setting)
Fig 1.4 Circuit to measure resistance
Procedure
To measure the voltage output of the power supply, we connected the voltmeter as shown in Fig. 1.1. We made sure that the voltmeter is always connected in parallel with the voltage being measured. Before turning on the power, we set the voltmeter voltage range to a DC value higher than the highest voltage we expected to measure. This precaution must be observed with all meters in order to avoid the possibility of burning out an expensive instrument.
We then set the current control to maximum current and adjust the output voltage of the supply to values of 2.5, 10, and 15.
Revenge is the opportunity to retaliate or gain satisfaction for a real or perceived slight ("revenge"). In “The Cask of Amontillado” by Edgar Allan Poe, Montresor, the narrator, is out for revenge. Montressor seeks revenge against Fortunato and thinks he has developed the perfect plan for “revenge with impunity” (Baym). Montresor never tells the reader why he feels Fortunato deserves punishment. He only says that Fortunato causes him “a thousand injuries”until “[venturing] upon insult” (Baym ?). As a result, Montresor plans to bury Fortunato alive.
The only problem with this experiment is that when the current passing through the battery circuit was at a continual rate there was...
Possible sources of error in this experiment include the inaccuracy of measurements, as correct measurements are vital for the experiment.
I found that my thermometer was slightly inaccurate, due to my measurements. Nothing is exact or perfect, but the thermometer is very close to accurate, being off in between 0.1-1°. This taught me that you cannot always trust a thermometer. The work has to be done by you individually to know what is really going
Oscilloscope is acquainted as one of the most helpful instrument for testing circuits. It is able to show the signals at different points in the circuit. One way to inves...
Planning Firstly here is a list of equipment I used. Boiling tubes Weighing scales Knife Paper towels 100% solution 0% solution (distilled water) measuring beakers potato chips Cork borer. We planned to start our experiment by doing some preliminary work. We planned to set up our experiment in the following way.
5. For the first test, test the amount of resistance when the large fan is off.
Two electrical wires * Stopwatch * Thermometer Method I put a piece of Elodea Canadensis (pond weed) in a test tube and covered it with water. The test tube was then placed in a beaker with a thermometer so that the water stayed the same temperature, this was then placed in a cardboard box with a bulb attached to a voltmeter by the electrical wires so that I could concentrate how much light the plant got. I varied the voltage (intensity) of the bulb and counted how many bubbles of oxygen were created at each voltage in one minute. I tested each voltage three times for accuracy for a minute each time. Results Preliminary Experiment Amount of bubbles Light intensity (lux)
it to a 5V power supply as a more convenient way of measure. As the
...inty between 1.0% (0.1/10.00*100) and 2.13% in the measured volume and 0.1/4.70*100). We also used a digital thermometer that allowed us to read the temperature readings from five degrees celcius to eighty degrees celcius. Since the digital thermometer have an absolute accuracy of plus or minus one degree celcius, it gives a percent uncertainty between 0.125 % (0.1 / 5.00 * 100) and 0.2 % (0.1/ 80.0 * 100). One of the difficulties we faced during the lab is reading the inverted graduated cylinder. To account for the inverse meniscus, we subtracted 0.2 mL from all the volumetric measurements to account for that. Volumetric uncertainty is the most important in determining the accuracy of this experiment since we are constantly checking for the volume throughout the lab. It also is the factor that gives the highest percent uncertainty out of all the instruments used.
Before learning the methods from the computer tutorial, I was confused about certain test. B...
3. Place a sheet of filter paper on to the scales and then set scales
This summer when you go to weigh that fat juicy watermelon, think about the mechanics of how the scale works. The basket is attached to a spring that stretches in response to the weight of the melon or other objects placed in it. The weight of the melon creates a downward force. This causes the spring to stretch and increase its upward force, which equalizes the difference between the two forces. As the spring is stretched, a dial calibrated to the spring registers a weight. When designing scales one needs to take into account that every spring has a different spring constant (k). Bloomfield (1997) defines k as “a measure of the spring’s stiffness. The larger the spring constant-that is, the stiffer the spring-the larger the restoring forces the spring exerts” (p. 82).
In the experiment there are several possible ways of changing the electric current such as changing the voltage or the position of the electrodes within the electrolysis cell. However, it was found from preliminary work that the most effective way to change the current was to change the concentration of the acid solution. The preliminary work showed that the greater the concentration of the acid, the greater the current. Ohm's law states that R(resistance) =
Then the ITS test is performed on the sample at 77°F (25°C) at a loading rate of 2in/min.