ECE 101 Exploring Electrical Engineering PSU

ECE 101 Exploring Electrical Engineering PSU

AS lab 2 and 3

ECE 101 Lab 2 and 3

Using a V-meter and A-meter, measure 3 samples each of one and the same low quality resistor, the same listed resistance. An optional expansion, if resistors are available: Repeat the same procedure with 3 identically sized resistors of high quality tolerance. Measure the varying, actual resistances –e.g. by using Ohm’s Law– between the 3 resistors of the same resistance.

Summarize findings in brief report. Also conclude, whether you agree with the quality ring information on the resistor. That conclusion is key to this lab.

Objectives:

1) Measurement of Actual resistance (Ractual) using Ohms law and verification of their tolerance value with their Nominal value.

2) Measurement, comparison and analysis of low and high tolerance values of Resistors using Ohms law.

Equipment:

a) Set of similar values resistors having different values of tolerance (20%, 10%, 5%,1%, 2%, and 0.1%)

b) DC Voltmeter and DC ammeter ( Multi meter).

c) Variable DC Power supply

Procedure:

i) Select 3 similar (identical) values of resistors having identical tolerance value (say 20% tolerance).

ii) Connect all 3 resistors and an ammeter in series to the DC Power supply as shown in figure 1.

figure 1

iii) Set proper range of DC ammeter and switch on the DC power supply. Set its output voltage of the power supply so that appropriate value of current should flow through the circuit.

iv) Measure the current (I1) in the circuit with the help of Ammeter. Using the DC voltmeter by selecting proper range, measure the voltage V1, V2, V3 across each resistor R1, R2, and R3 respectively. Note down the values of current (I1), voltage V1, V2 and V3 across resistor R1, R2 and R3 in the table T 1.1.

v) Using Ohms law calculate the Actual values of Resistors, R1= V1/(I1), R2=V2/(I1) and R3= V3/(I1).

vi) Next, make a small increment of current through the circuit by changing the DC supply Voltage to a next convenient value and note down the current (I2), and voltage across each resistors. Tabulate the readings.

vii) Once again calculate the values of R1, R2 and R3 for the increased value of current.

viii) Repeat the above procedure for another set of current.

ix) Compare the Actual values of Resistance R1, R2 and R3 with their Nominal value of Resistances and analyze them with respect to specified tolerance value of the resistors.

x) Replace the resistors in the circuit by similar resistor values having better tolerance value say (10%) and repeat the above procedure step (iii) to (ix).

xi) Again repeat the above procedure by replacing resistors having still better tolerance values say (5%) and (2%).

xii) Compare the measured (Actual) resistance values with their nominal values and write down your findings on the quality of the resistors with respect to their tolerance as conclusion.

For Tolerance =20%
Current I
in mA / Voltage V1
In Volts / Voltage V2
In Volts / Voltage V3
In Volts / Resistor R1
R1= V1/I / Resistor R2
R2= V2/I / Resistor R3
R3= V3/I
I1= I=
I2= I=
I3= I=
For Tolerance =10%
I1= I=
I2= I=
I3=I=
For Tolerance=5%
I1= I=
I2= I=
I3= I=
For Tolerance=2%
I1= I=
I2= I=
I3=I=

Table T 1.1

FOR LAB 3

Do the same as in lab 2, but measure some of the units using an oscilloscope, or using an Ohm-meter. Important that you use the identical electric components as in Lab 2.

Summarize your findings again in a brief report and conclude, whether or not measuring with an Ohm-meter (or oscilloscope) generated different quality results, versus the A-meter and V-meter method used in Lab 2.

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