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Xavier UniversityCollege of EngineeringChemical Engineering

Experiment Number: 1Experiment Title: Multimeters

Date Performed: July 7, 2010 Subject: ACE 03FDate Submitted: July 14, 2010 Group Number: 7

Group Leader : Mark Julius R. CabasanGroup Member/s: Ashton Leo Gaoiran

Mark Anthony MarayaDuane BroseTracy Eduria

Presentation : ___________________Data and Results : ___________________

Analysis and Conclusions : ___________________ Answers to Questions : ___________________

Total : ___________________

Remarks: ___________________________________________________________________________________________________________________________________________________________________________

Instructor : Engr. Jose Mag-abo IIInstructors Signature : ________________________

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I. Objectives:

The objectives of the study were to determine the difference between an analog

multimeter and a digital multimeter, to measure the voltage, current and resistance and

to compare the accuracy of the two multimeters.

II. Introductory Information/Theory

Multimeters are electrical instrument capable of measuring voltage, current, and

resistance. By the use of a multi-position switch on the meter they can be quickly and

easily set to be a voltmeter, an ammeter or an ohmmeter. They have several settings

and ranges for each type of meter and the choice of AC or DC. Some multimeters have

additional features such as transistor testing and ranges for measuring capacitance and

frequency.

Digital multimeters

Digital multimeters have numerical displays for indicating the quantity of voltage,

current, or resistance. All digital multimeters contain a battery to power the display so

they use virtually no power from the circuit under test. This means that on their DC

voltage ranges they have a very high resistance (usually called input impedance) of 1M

or more, usually 10M, and they are very unlikely to affect the circuit under test.

Digital meters have a special diode test setting because their resistance ranges

cannot be used to test diodes and other semiconductors.

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Analogue multimeters

Analog multimeters are less expensive than digital multimeters, and more

beneficial as learning tools for the first-time student of electricity. Analogue meters takea little power from the circuit under test to operate their pointer. They must have a high

sensitivity of at least 20k/V or they may upset the circuit under test and give an incorrect

reading. See the section below on sensitivity for more details.

Batteries inside the meter provide power for the resistance ranges, they will last

several years but you should avoid leaving the meter set to a resistance range in case

the leads touch accidentally and run the battery flat.

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III. Materials Needed

The materials needed for the experiment were Analog and Digital multimeters,

individual resistors, regulated power supply and connection box.

IV. Procedure

1. Voltage measurement

Set the analog meter to DCV 10 and the digital to DC and V 40 and connect both

meters to an adjustable power supply. The box at the left shows a picture display and a

schematic diagram of the connection. Note that all + terminals are connected together

(parallel connection). Vary the voltage source in one volt steps, so that the analog

meter reads exactly 1.0, 2.0, 3.0,, 10.0, and for each value record the digital reading.

Display your results in a neat table.

2. Current measurement

Set the analog meter to DCmA 25 and the digtal to DC and A 40m. Connect as

shown in the diagram. Notice that the same current flows through each circuit element

(series connection), and the + terminal of the power supply is connected to the +

terminal of the meter. Vary the power source so that the analog meter reads exactly 1.0,

2.0, 3.0,, 10.0 milliamperes, and the record the corresponding reading of the digital

meter.

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3. Resistance measurement

Before each resistance measurement with the analog meter, connect the input

terminals together and adjust the Zero Ohms knob, so that the needle points to 0 on the

top - scale.

The decade resistance box has six dials, marked 100K, 10K, 1K, 100, 10, and 1.

These values are multipliers, so that the contribution of each dial to the total resistance

is the dial reading times the multiplier. The accuracy of each dial is approximately 1 %.

Set the dials to read, in succession, values of 862000, 33500, 2670, 334, 72, and 8. For

each setting, measure the resistance first with the analog, then with the digital meter

and record measurements in a neat table; select the range value which gives the most

precision. Do not connect both meters at the same time to the decade resistance box.

NOTE: If a decade resistance box ix not available, use a set of six resistors, one each

with the resistance somewhere within the ranges of the individual decade dials.

V. Data and Results

VOLTAGE MEASUREMENTS

ANALOG DIGITAL ANALOG DIGITA

1.00 0.99 6.00 6.01

2.00 1.94 7.00 7.03

3.00 3.01 8.00 8.094.00 4.02 9.00 9.05

5.00 4.95 10.00 10.18

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CURRENT MEASUREMENTS:

ANALOG

80 16.5

85 18.4

90 18.6

95 19.6

100 21.0

RESISTANCE MEASUREMENTS

PRE-SET ANALOG DIGITAL

100 100 99.3

100 K 80 98

1.8 M 1.8 M 1.8 K

200 K 168 K 169.1 K

18 25 K 18 K

2.7 K 2.7 K 2.64 K

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VI. Analysis and Conclusion

Multimeters indicate the presence of voltage, current, and resistance, and

measure the quantity. Voltage is the measure of electrical push ready to motivate

electrons to move through a conductor and it is measured in the unit of volt. On the

other hand, resistance is the measure of electrical friction as electrons move through

a conductor and it is measured on the unit of the ohm. That is why the experiment was

divided into three parts: the determinations of voltage, resistance and current. While

current means, depending on the context, a flow of electric charge or the rate of flow of

electric charge.

The voltage and power source was varied in order to obtain readings in the

analog meter to reads exactly 1.0, 2.0..., 10.0. The measured values were then

tabulated. As observed in the table of data for voltage and current, the readings of the

analog yields less difference. The results for the current measurements were adjusted

to 80, 85, 90, 95 and 100 due to a high readings for the analog and consequently

consequently yielded low readings for the digital multimeters with an average of 78.8

percentage difference from the analog multimeter. For resistance measurements, the

readings of the analog and the digital were near to each other except for the pre-set

values of 100 K and 200 K having percentage error of 20% and 16% respectively.

Equally, the digital multimeter and analog multimeter are effective tools for

measuring electrical quantities but the digital multimeter proved to be more accurate

than the latter. Reading the analog multimeter could lead to measurements. On the

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contrary, the digital multimeter could read from 3 (three) to 4 (four) significant figures

depending on the selection of range.

In summary, both are effective electrical instruments capable of measuring

voltage, current, and resistance but digital multimeters have numerical displayswhich

makes it most accurate than an analog multimeter.