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To measure unknown frequency & capacitance using Wien’s bridge.

OBJECT:- To measure unknown frequency & capacitance using Wien’s bridge.

APPRATUS REQUIRED :- Trainer kit and patch cords

THEORY:-

Wein Bridge is used as an AC Bridge. This is used to measure frequency. Wein Bridge is used as a notch filter in the harmonic distortion analyzer, also used in audio and high frequency oscillators as the frequency determining element.

The Wein Bridge used for the measurement of frequency is shown in this bridge has a series RC combination in one arm and a parallel RC combination in the adjoining arm.

 

CIRCUIT DIAGRAM:-

 

Fig4.1:- Wein Bridge to calculate unknown frequency and capacitance

FORMULA USED:-

The unknown capacitance is calculated by

C2/C1 = R2/R1 - R3/R4

The unknown frequency is calculated by            

F = (1 / 2π) x (1/√ ( [R3R4C1C2])).

take C1=C2=C and R3=R4=R.

F= 1/ 2πRC

 

 

PROCEDURE:-

  1. Connection to be made as per the circuit diagram
  2. The balance condition is obtained by adjusting capacitance in the bridge
  3. Adjust R2, R3, and R4 in sequence repeatedly till the volume of the head phone is minimum possible or its not heard at all.
  4. All the values in the bridge are noted down.

OBSERVATION TABLE :-

S.No.

Set Frequency

R1

R2

R3=R4=R

C

F=1/2πRC

1

 

 

 

 

 

 

2

 

 

 

 

 

 

 

RESULT: - The unknown frequency is measured using Wien’s Bridge successfully.

PRECAUTION:-

  1. Check all the connections before turning ON the power supply.
  2. Note the reading carefully.

QUESTIONS:-

  1. What is notch filter?
  2. Write the applications of Wein’s Bridge?

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