Electronic Instrumentation and Measurements.

  1. Explain gross errors, systematic errors, absolute errors and relative errors. Give examples of each.
  2. Calculate the maximum percentage error in the sum of two voltage measurements when V1 = 100 V ± 1% and V2 = 80 V ± 5%.
  3. Sketch the basic construction of a typical PMMC instrument. Identify each parts of the instrument and explain its operation.
  4. A moving coil ammeter has a fixed shunt of 0.02Ω with a coil circuit resistance of R = 1kΩ and needs potential difference of 0.5 V across it for full scale deflection.
    • Calculate the current it corresponds to.
    • Find the value of shunt when the total current is 10 Amperes.
  5. Sketch the construction of electrodynamometer type instruments. Briefly explain their operation.
  6. The inductance of a moving iron ammeter is given by the following expression. L = (30 + 10φ + 2φ2)μH where φ is the deflection in radians. The control spring constant is 25 x 10-6 N-m/rad. Calculate the value of deflection for a current of 5A.
  7. Sketch a basic block diagram for dual-slope-integrator digital voltmeter and briefly explain its operation. Explain why a DVM using dual slope integrator is more accurate than linear ramp type DVM.
  8. Sketch the circuit for Maxwell and Schering Bridges, explain their operation, and derive their balance equations.
  9. How can frequency be determined using a bridge ? Draw this bridge and derive condition for balance. Why and how two resistances and capacitances are made equal ?
  10. Sketch the basic construction of a CRT. Identify each section of the tube and show typical supply voltages at each appropriate point. Carefully explain the operation of the CRT.
  11. Explain with the help of functional block diagram, the principle of operation of a digital frequency meter.
  12. How can frequency be determined using a bridge ? Draw this bridge and derive condition for balance. Why and how are two resistances and capacitances made equal ?
  13. What are the classifications of transducers ? How does a Piezo-Electric transducer work ? What are the common materials used for it ? Draw an equivalent circuit and practical circuit for this transducer.
  14. What are the advantages of a digital voltmeter over analog type? Explain the working of ramp type digital voltmeter. In a linear ramp type voltmeter, the counter is drawn by a 0.5MHz clock and the value of the counter is 200 at the end of the measurement.
  15. Write short notes:
    • Q-meters
    • Phase locked loop
    • Cathode Ray Oscilloscope
    • LVDT
  16. Resistors R1 and R2 have the nominal value 3Ω and 6Ω and tolerance of ±10% and and ±5% respectively. What would be the equivalent resistance value when R1 and R2 are connected in parallel.
  17. Explain the working of binary ladder digital to analog converter using R-2R ladder network with four input voltages.
  18. If in the above DAC, a reference voltage 12V is used, what will be its resolution and full scale output voltage ?
  19. What are the different problems associated with measurement of low resistances? Explain the principle of working of Kelvin’s Double Bridge and how the effect of contact resistance of leads is eliminated.
  20. A balanced bridge has the following arm parameters:
    • Arm AB: R1 = 1500Ω in parallel with C1 = 0.03μF,
    • Arm BC: R2 = 1876Ω in series with C2 = 0.03μF,
    • Arm CD: unknown and
    • Arm DA: C3 = 0.5μF.
    • If an a.c. voltage of frequency 1kHz is applied across the junction BD, find the parameter of arm CD.
  21. A moving coil ammeter has a fixed shunt of 0.02Ω with a coil circuit resistance of R = 1kΩ and needs potential difference of 0.5V across it for full deflection.
    • Calculate the current it corresponds to.
    • Find the value of shunt resistance when the total current is 10A.
  22. Resistors L1 and L2 have the nominal value 3H and 6H and tolerance of ±10% and and ±5% respectively.
  23. What would be the equivalent inductance value when L1 and L2 are connected in parallel.
  24. Explain the working of binary ladder digital to analog converter using R-2R ladder network with three input voltages.
  25. If in the above DAC, a reference voltage 12V is used, what will be its resolution and full scale output voltage ?
  26. Which bridge is used for measurement of medium quality factor? Explain the principle of working of Anderson Bridge.
  27. A moving coil ammeter has a fixed shunt of 0.05 Ω with a coil circuit resistance of R = 2kΩ and needs potential difference of 1V across it for full deflection.
    • Calculate the current it corresponds to.
    • Find the value of shunt resistance when the total current is 5A.
  28. Resistors R1 and R2 have the nominal value 3 Ω and 5 Ω and tolerance of ±10% and and ±5% respectively. What would be equivalent resistance value when R1 and R2 are connected in parallel.
  29. Explain the working of binary ladder digital to analog converter using R-2R ladder network with four input voltages.
  30. If in the above DAC, a reference voltage 12V is used, what will be its resolution and full scale output voltage.
  31. What are the different problems associated with measurement of low resistances ? Explain the principle of working of Kelvin’s Double Bridge and how the effect of contact resistance of leads is eliminated.
  32. A balanced bridge has the following arm paratmeters:
    • Arm AB: R1 = 1500 ohm in parallel with C1 = 0.03 µF,
    • Arm BC: R2 = 1876 ohm in series with C2 = 0.03 µF,
    • Arm CD: unknown and
    • Arm DA: C3 = 0.5 µF.
      • If an a.c frequency 1kHz is applied across the junction BD, find the parameter of arm CD.
  33. A moving coil ammeter has a fixed stunt of 0.02 Ω with a coil circuit resistance of R = 1 kΩ and needs potential difference of 0.5V across it for full deflection.
    • (a) Calculate the current it corresponds to.
      (b) Find the value of shunt resistance when the total current is 10A.