Lab-Engineer

Certificate

Certified that Mr.

/Miss.__________________________________

S/O/D/O ____________________________of 4st Term

2rdYear of Electrical Engineering has carried out the

necessary practical work for the subject of APPLIED

ELECTRONICS prescribed by the Mehran University

of Engineering & Technology SZAB Campus

Khairpur Mir’s

S # OBJECT1 To become familiar with the working principle of LDR.

2 Characteristics curve of phototransistor.

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LAB EXPERIMENT # 01

Name: Roll #

Score: Signature of Lab Tutor Date:

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OBJECT :

To become familiar with the working principle of LDR.

EQUIPMENT :

LDR, Resistor, Battery (9V), Transistor (BC547), LED, Breadboard and Connecting wires.

THEORY:

LDR is a two terminal electronic component. It is a light dependent resistor, its resistance decreases when intensity of light increases vice versa.

PROCEDURE:

Connect all the components as shown below in the circuit.

RESULT:

In the practical we observed that when we increase the intensity of light LED glow and vice versa means when LED glow there was a minimum resistance due to that there was a sufficient current to glow the LED and vice versa.

VIVA QUESTIONS

Q1: what is the relationship between the light of intensity and resistance of LDR?

Ans: ____________________________________________________________.

Q2: LDR stand for?

Ans: ____________________________________________________________.

LAB EXPERIMENT # 02

Name: Roll #

Score: Signature of Lab Tutor Date:

OBJECT:

Characteristics curve of phototransistor.

EQUIPMENT:

Phototransistor, Transistor BC 547, 9V battery, Connecting wire, LED and Breadboard

THEORY:

Phototransistor has a light sensitive CB junction. A lense is used in a transistor package to expose base to light when no light is incident a small leakage current flow from collector to emitter called Iceo due to small thermally generation. This is very small in mA this is

called dark current. When base is expose to light Ib is produces, Ib is proportional to light of intensity each photon induce base current denoted by I, the resulting current is given by Ic= . and larger the area of the base is expose to light.

PROCEDURE:

Connect the components as shown below in the circuit.

RESULTANT CHARACTERISTIC CURVE:

VIVA QUESTIONS

Q1: If there is a maximum intensity of light what will be voltage across the R1?

Ans:_______________________________________________________________________.

Q2: If intensity of light is minimum what will be voltage across the phototransistor?

Ans:_______________________________________________________________________.

Q3: Why we use convex lens in phototransistor?

Ans:_______________________________________________________________________.