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Lab # 1: Resistor Color Coding .

Apparatus: Resistors, Digital Multimeter(DMM).

Procedure:

Identifying the value of color coded resistors will become easy with a little practice,

as there are only a few simple rules to remember.

The 4 band code is used for marking low precision resistors with 5%, 10% and 20%

tolerances. The first two bands represent the most significant digits of the

resistance value. The third band indicates the multiplier telling you how many zeros

to add. If the multiplier band is gold or silver then the decimal is moved to the left by

one or two places (divided by 10 or 100). The tolerance band (the deviation from

the specified value) is next, usually spaced away from the others, or it's a little bit

Note: 20% resistors have only 3 color bands - the tolerance band is missing.

The standard resistor color code table:

Colors 1st band 2nd band3rd bandMultiplier

Tolerance

Black 0 0 100 -

Brown 1 1 101 -

Red 2 2 102 -Orange 3 3 103 -

Yellow 4 4 104 -

Green 5 5 105 -

Blue 6 6 106 -

Violet 7 7 107 -

Gray 8 8 108 -

White 9 9 109 -

Gold - - 0.1 5%

Silver - - 0.01 10%

None - - - 20%

The colors brown, red, green, blue, and violet are used as tolerance codes on 5-band resistors

only. All 5-band resistors use a colored tolerance band. The blank (20%) "band" is only used

with the "4-band" code (3 colored bands + a blank "band").

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Example: 1

A resistor colored Yellow-Violet-Brown-Gold would be 470 with a tolerance of

5%.

Rmax = 493.5

Rmin = 446.5

Example: 2

A resistor colored Green-Blue-Gold-Gold would be 5.6 with a tolerance of

5%.

Rmax = 5.88

Rmin = 5.52

Lab # 2: To use DMM as voltmeter for verifying KVL.

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Equipment: Resistors, Digital Multimeter(DMM), Power Supply, Connecting Wires,Bread Board (Solder Less)

DMM Introduction:

The DMM is an instrument which can be used to measure DC (non-time-varying)

voltages and currents, AC (time-varying) voltages and currents, and resistance

values. Signals are input to the DMM through two leads (red for positive, and black

for negative), and then the value measured is displayed.

Internally the meter can read only DC voltages. An A/D (analog-to-digital)

converter is used to convert DC voltages to a digital code. Thus to measure current

or resistance, the signal must be converted into a voltage value. For current, this is

easily done by placing a (very small) precision resistor in the circuit and measuring

the voltage across the resistor, which will be linearly proportional to the current.

Resistance measurements require more circuitry because a resistor is a passive

element, thus a source must be provided in the DMM. In the DMM there is a current

source to force a current through the resistor and the voltage is then measured.

From this information the resistance value may be determined by Ohms Law:

R = V/ I

Additional circuitry is necessary to allow variable ranges. For voltage and

resistance measurements, this consists of various voltage-divider networks which are

switched in. For current measurements it consists of different resistors to be

switched in. Also, an RMS (root mean square) circuit is used to convert the AC

voltages to DC voltages. The DC voltage given is the square root of the average

value of the input voltage squared.

2)(INOUT

VV =

Theory:In a series circuit, the current is the same through all of the circuit elements.

The total Resistance RT =R1 + R2 + R3.

By Ohms Law, the Current I is

I = V/R

Applying Kirchoffs Voltage Law around closed loop of Fig, we find.

VT = V1 + V2 + V3

Where, V1= IR1, V2= IR2, V3=IR3

Note in Fig, that I is the same throughout the Circuit.

Procedure:

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First I constructed the given ckt on bread board. Then I connected Three Resistors in

series and a 30v DC supply. I observed the VT(Sum Of Voltages) of DC supply as

given in observation table. And then I measured / found the voltages across each

resistor.

I took minimum of three readings for verifying the KVL.

S. No. V1 V2 V3V1+V2+

V3VT

1 2.01v 3.40v 3.94v 9.35v 10v

2 2.95v 3.42v 3.85v 10.22v 11v

3 1.74v 3.23v 3.94v 8.91v 9v

Conclusion:

As we Know from the statement of KVL, it can be stated as such:

"The algebraic sum of all voltages in a loop must equal zero" which is now

verified from the above Observation.

Lab #3: To use DMM as Ammeter for verifying KCL

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Equipment: Resistors, Digital Multimeter(DMM), Power Supply, Connecting Wires,

Bread Board (Solder Less).

Theory:

In a parallel circuit (fig) the voltage across parallel elements is the same.

The total or equivalent resistance (RT) is given by.

1 1 1 1 1

= + + + + RN

RT R1 R2 R3

If there are only two resistors in parallel, it is more convenient to use.

R1R2

RT

=R1

In any case, the total resistance will always be less than the resistance of the

smallest resistor of the parallel network.

For the network of Fig. The currents are related by the following expression.

IT =I1+ I2+ I3+-----------+ IN.

Procedure:First I constructed the given ckt on bread board. Then I connected Three

Resistors in Parallel with a 30v DC supply. I observed the I T(Sum of All Currents) of

DC supply as given in observation table. And then I measured / found the Currents

across each resistor.

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I took minimum of three readings for verifying the KCL.

S. No.I1

(mA)

I2

(mA)

I3

(mA)

I1+I2+I3

(mA)

IT

(mA)

1. 2.34 1.31 0.96 4.61 4.65

2. 2.20 1.41 0.90 4.50 4.55

3. 3.05 1.50 0.70 5.25 5.30

Conclusion:

As we Know from the statement of KCL, it can be stated as such:

"The algebraic sum of all currents entering and exiting a node must beequal to zero" verified from the above Observation.

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Lab 04: Introduction to Oscilloscope &

Function Generator

a) Oscilloscope:

Calibration.

Functional Check.

Various Functions of Oscilloscope.

Display waveforms on screen.

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b) Function Generator:

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Lab #5: To study Bridge Rectifier using Oscilloscope

Apparatus:AC Supply 20v,

Bridge Rectifier,

Oscilloscope with probes,

Connecting Wires.

Theory:

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Input

Time F=1/T VP.P VP Vrms =Vp/

2boxes10ms=20ms

1/20ms =50Hz 5.2x5 =25.1v 3.15v =15.5v 10v

Output

T F=1/T VP Vrms

0.011sec 99Hz 11v 15.56

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