Experiment Simple Voltage and Current MeasurementObjectiveThe 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 10 V scale is accurate to (+/- 0. 03%) (10) = +/- 0. 3 V. Thus, a reading of 9 V on the 10 V scale indicates a true voltage, which lies between 8.
7 and 9. 3 V. A reading of 1 Von 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 ab a b a ad c c dc d Fig 1.
The Essay on Circuits Experiment
1. Describe the type of meter movement used in analog meters. The current in the circuit is used in basic meters to measure the voltage drop or current in the circuit. The current passes through the coils of wires, which is then magnetized. Inside the apparatus, there is also a permanent magnet which opposes the magnetic field of the magnetized coil of wire that is connected to the pointer ...
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. We made sure to set the range switch of the voltmeter to a suitable scale before changing the voltage. By using 3% tolerance for the meter, we determined the range of the true voltages at each setting. The values are showing in Table 1.
1. We then set up the circuits shown in Fig. 1. 2.
We measured and recorded the voltage and placed the values in Table 1. 2 for: (a) Vab = Vdc = 3 V (b) Vab = 5 V, Vdc = 10 To measure the voltage output of the power supply, we connected the ammeter as shown in Fig. 1. 3. In order to measure the current, we made sure to insert the ammeter in series in the wire in which the current was flowing.
By varying the supply, Vs, between 0 and 10 V we measured and recorded the current, I, and placed the values in Table 1. 3. To determine the resistance we set up the circuit in Fig. 1. 4 where RX is any resistor with a value between 1 k’U and 10 k’U.
We pretend that Rx in unknown. For 4 different values of Ix, we recorded Vx in an appropriate table by measuring with voltmeter / ammeter. We then plot a Ix x Vx graph. We made sure that the points on the graph lie on a straight line of slope 1/Rx. We noticed at the end that the resistor was 2 k. Tables Table 1.
The Term Paper on Microcontroller Based LCR Meter
A microcontroller based scheme for LCR measurement is described. The unknown element (an inductor or a capacitor or a resistor) is measured employing a non conventional ac bridge. The element to be measured forms one arm (side) of the bridge and the second (series) arm is made up of a simple resistor. A Multiplier type Digital to Analog Converter (MDAC), controlled by a microcontroller, serves as ...
1 Power Supply versus Voltmeter voltage (Fig 1. 1) Meter Reading, V True Voltage Range 2. 5 2. 410 9.
915 14. 9 Table 1. 2 Simple voltage measurement (Fig 1. 2) Vab Vdc Vac Vad 3 3 6.
21 05 10 0 -4. 96 Table 1. 3 Current measurement (Fig 1. 3) Resistance k’U Vs I (mA) 1 2 2. 041 4 4. 91 6 5.
991 8 8. 011 10 9. 98 Table 1. 4 Resistance measurement (Fig 1. 4) Ix (A) Vx (V) Rx (‘U) Slope of the line 1.
02 2. 04 2. 0032. 02 4. 04 1. 9913.
04 6. 04 1. 9934. 04 8.
01 1. 993 Conclusion In this experiment I learned the basics theory behind Ohm’s Law, and I put it to use in the experiment. I also learned how to use measurement devices such as voltmeters, Ohmmeter, and ammeters. Some error in the lab was cause by the inaccuracy of the dial on the power supply that’s set the initial voltage. Answer to Questions 1) The precautions that must be taken before connecting any meter into a circuit is to set the meter at its maximum current so we do not damage the meter. 2) A voltmeter is connected in parallel to measure unknown voltage.
3) It is bet to obtain a meter reading as far upscale as possible because the needle of the meter castes a shadow on the meter and it makes it difficult to read. 4) An ammeter is connected in series to measure unknown current.
