EXPERIMENT 2: RESISTOR, COLOUR CODES & DIODES

2.1 Objective

1. To determine the resistance of a resistor by using:

a) Colour codes

b) Digital ohmmeter

c) Analogue ohmmeter

2. To determine anode and cathode, built-in-voltage and the material of a diode.

2.2 Abstract

A diode can be measured with a digital and analogue multimeter. The techniques used for

each type of meter are very different so they are treated separately. Digital multimeter has a

special setting for testing a diode, usually labeled with the diode symbol which the read (+) lead

connected to the anode and the black (-) connected to the cathode. The diode should conduct and

the meter will display a value (usually the voltage across the diode in mV, 1000mV = 1V).

Reverse the connections. The diode should NOT conduct this way so the meter will display "off

the scale" (usually blank except for a 1 on the left). When use the analogue mulimeter to test

diode, the analogue multimeter must be adjusted to a low value resistance range such as × 10. It

is essential to note that the polarity of analogue multimeter leads is reversed on the resistance

ranges, so the black lead is positive (+) and the red lead is negative (-)! This is unfortunate, but it

is due to the way the meter works. The black (+) lead connected to anode and the red (-)

connected to the cathode. The diode should conduct and the meter will display a low resistance

(the exact value is not relevant). Reverse the connections. The diode should NOT conduct this

way so the meter will show infinite resistance (on the left of the scale).

2.3 Introduction

A resistor is a passive two-terminal electrical component that implements electrical

resistance as a circuit element. The resistor is the most common electronic component and is

used to limit and/or control the voltage and current in an electronic circuit. Resistors are carefully

manufactured to provide a predetermined value of electrical resistance which may range from 0.1

ohms to 100,000,000 ohms, depending on the application. The current through a resistor is

indirect proportion to the voltage across the resistor's terminals. Thus, the ratio of the voltage

applied across a resistor's terminals to the intensity of current through the circuit is called

resistance. This relation is represented by Ohm's law:

Where:

 I= The current through the conductor in units of amperes.

V =The potential difference measured across the conductor in units of volts.

R= The resistance of the conductor in units of ohms. 

The ohm  and symbol Ωis the SI unit of electrical resistance. An ohm is equivalent to

a volt per ampere

Picture 1: The symbol of resistor in circuit. Picture 2: The basic symbol of resistor

In electronics, a diode is a type of two-terminal electronic compenant with nonlinear

resistance and conductance distinguishing it from compenant such as two- terminal linear

resistors which obey Ohm's law. A semiconductor diode, the most common type today, is

a crystalline piece of semiconductor material connected to two electrical terminals. A diode is an

electronic device that allows electricity to flow in only one direction. It acts as a valve, of sorts.

When the term "measuring" is used in relation to a diode, it is actually referring to measuring the

forward voltage drop across the diode. This drop is measured in volts and is usually very small.

Measuring this drop requires a multimeter that has this capability. The diode check works by

forcing a small amount of electrical current into the diode and then measuring the difference, or

voltage drop on the other side.

Picture 3: The picture of diode Picture 4: The symbol of diode

Picture 5: The way to setup and measured the value diode

2.4 Apparatus

Picture 6: Resistor

1. Resistors

2. Diode 1 (IN4001)

3. Diode 2 (IN4002)

4. Digital ohmmeter

5. Analogue ohmmeter

2.5 Procedures

PART A- Resistor and Colours Code

1. The variety of resistor with difference colour code was observed.

2. The resistor was taken and the colour was determine to the suitable value according to the

given scheme.

3. A central knob digital multimeter was adjusted so that it is appropriate to the

measurement value.

4. The value of the resistor was taken by using the digital multimeter. The value was

recorded in table 1.

5. A central knob of analogue multimeter was adjusted to the appropriate measurement

value.

6. The value of resistor was taken by using analogue multimeter. The result was recorded in

Table 1.

7. Step 2-6 was repeated for each resistor.

PART B- Diode

1. A IN4001 and IN4002 diode was choosed.

2. A central knob of digital multimeter was adjusted to the symbol of diode.

3. The value of IN4001 diode was taken. The reading was recorded in Table 2.

4. The measurement of a central knob analogue was taken.

5. The value of a IN4001 diode was taken by using analogue multimeter. The reading was

recorded in Table 2.

6. The anode and cathode was draw and labeled.

7. Step 2-7 was repeated for IN4002.

2.6 Result

PART A – Resistor and colour code

RESISTO

R

COLOUR CODE ( ) DOM ( ) AOM( )

1 1000 ± 5% 0.987 K 0.90 K

2 220 ± 5% 215.8 250

PART 2: DIODE

DIODE DOM (Ὠ ) AOM (Ὠ )

1 (IN4001) 0.553V 1.468 K Ὠ 0.550 V No value

2 (IN4002) 0.555 V 1.69K Ὠ 0.550 V No value

2.7 DISCUSSION

From the result in part 1, the value of colour code for resistor 1 is 1000 ± 5%. while ,

the reading of digital multimeter is 0.987 K . It is different to the reading of analogue

multimeter which is 0.90 K . The value of colour code for resistor 2 is 220 ± 5%. while , the

reading of digital multimeter is 215.8 . It is different to the reading of analogue multimeter

which is 250 . Either a digital or analog multimeter or ohmmeter is fine for testing a resistor,

but digital meters are more useful because they give you a precise reading and digital

multimeter a better than analog multimeter, as the chances of making a mistake in taking a

correct reading decreases to a large extent. For the colour code, a resistor of tolerance 1% is

accurate, but still not perfect. For this resistor, show that we get the tolerance is 5% which

nearest to inaccurate value.

Based on the experiment in part 2, the diode can be measured with digital and analogue

multimeter. The value of the IN4001 diode is 0.553 V ant the resistance value is 1.468X103Ohm

when calculate by using digital multimeter. When we measure by using analogue multimeter, the

value is 0.550 V and the resistance cannot be measured. For the IN4002 diode, when use the

digital multimeter, the value is 0.555 V and the resistance value is 1.69X103 Ohm. When we used

analogue multimeter the value is 0.550 V and he resisitance cannot be measured. With digital

multimeter, we able to measure the diode in voltage and resistance value which give different

value. Indeed, we unable to get ohm value of diode when we use analogue multimeter. This is

because maybe there are problem with digital analogue such as low battery.

2.8 Precaution

The resistance value of resistor has a slightly different when we calculate by using the

colour table (manually) by referred the colour of resistor and measure by using digital multimeter

and analogue multimeter. This error may be caused by the parallax error. This error happen when

we used the analogue multimeter to measure the resistance of resistor. To overcome this error,

we should use the mirror at the surface of the scale reading to take the reading.

The second error is the analytical error. This error is the caused by the broken of

apparatus use. Example the apparatus is low in charge. This error will affect our result. To

overcome this error, we need to make sure that the apparatus that we need to use is in standby

condition and have no error such low in charge.

Finally is zero error, the apparatus may have the zero error. To overcome this error, make

sure before use the apparatus; we need to adjust the needle of the scale to the zero number to get

the accurate reading.

2.9 Conclusion

As the conclusion the digital and analogue multimeter can be used to measure the value

of diode and resistor. Indeed, the voltage and resistance range are two units that can measure the

diode. The digital multimeter is most accurate in reading the voltage and resistance of diode and

resistor than analogue multimeter.

2.9 APPENDIX

Table 1: Resistor colour code

3.0 Reference

1. Charles Schuler (2008). Electronics Principle and Application (7th Ed): NEW YORK,

McGraw-Hill Companies, Inc.

2. Cutnell J.D, Johnson W.K (2010). Introduction To Physics (8th Ed): USA. John Wiley &

Sons Pte Ltd

3. http://www.ehow.com/how_7802810_measure-diode.html

4. http://integrated-thoughts.blogspot.com/2011/05/doide.html

5. http://en.wikipedia.org/wiki/Diode