Emi Labs 1-5

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 band

Black Brown Red Orange Yellow Green Blue Violet Gray White Gold Silver None

0 1 2 3 4 5 6 7 8 9 -

0 1 2 3 4 5 6 7 8 9 -

3rd band Multiplier ×100 ×101 ×102 ×103 ×104 ×105 ×106 ×107 ×108 ×109 ×0.1 ×0.01 -

Tolerance ±5% ±10% ±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").

1.

Example: 1

A resistor colored Yellow-Violet-Brown-Gold would be 470 Ω with a tolerance of ± 5%. Rmax = 493.5 Ω Rmin = 446.5 Ω

Example: 2

A resistor colored Green-Blue-Gold-Gold would be 5.6 Ω with a tolerance of ± 5%. Rmax = 5.88 Ω Rmin = 5.52 Ω

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

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 Ohm’s 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.

VOUT = (V IN ) 2

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

RT =R1 + R2 + R3.

By Ohm’s Law, the Current “I” is I = V/R Applying Kirchoff’s 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: 3.

First I constructed the given ckt on bread board. Then I connected Three Resistors in series and a 30v DC supply. I observed the V T(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.

V1+V2+

S. No.

V1

V2

V3

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

V3

VT

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 4.

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 =

RT

+

R1

1 +

R2

1 +

R3

… … … + RN

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

R1R2

       RT  =     

  

R2

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.

5.

I took minimum of three readings for verifying the KCL.

I1

I2

I3

I 1+I 2+I 3

IT

(mA)

(mA)

(mA)

(mA)

(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

S. No.

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 be equal to zero" verified from the above Observation.

6.

Lab 04: Introduction to Oscilloscope & Function Generator a) Oscilloscope: •

Calibration.

•

Functional Check.

•

Various Functions of Oscilloscope.

•

Display waveforms on screen.

7.

8.

9.

10.

11.

12.

13.

14.

15.

b) Function Generator:

16.

Lab #5: To study Bridge Rectifier using Oscilloscope

Apparatus:

AC Supply 20v, Bridge Rectifier, Oscilloscope with probes, Connecting Wires.

Theory:

17.

Input Time

F=1/T

VP.P

VP

2boxes×10ms =20ms

1/20ms =50Hz

5.2x5 =25.1v

3.1×5v =15.5v

Vrms =Vp/

10v

Output

T

F=1/T

VP

Vrms

0.011sec

99Hz

11v

15.56

18.