1. What is air core inductance ?

The inductance that would be measured if the core had unity permeability and the flux distribution remained unaltered. (A measure of the inductance of a coil without a core).

2. What do you mean by Balance?

A weighing machine. The terms scale and balance are often used interchangeably. a balance was a device that determined mass by balancing an unknown mass against a known mass as with a 2 pan assay balance.

3. Define Viscosity.

It is a measure of fluidity of the system. Many fluids undergo continuous deformation with the application of shearing stress.

4. Define Newtonian fluids

If the force flow relation is linear then the fluid is Newtonian .

5. Define Non Newtonian fluids

If the force flow relation is non linear then the fluid is Newtonian .

6. Define Kinematic Viscosity.

Ratio of absolute viscosity to the density of the fluid. V= µ cm2 /ς sec

7. Define Specific Viscosity.

Ratio of absolute viscosity of the fluid to the absolute viscosity of a standard fluid at the same temperature. µs = µ / µh

8. Define Relative Viscosity.

Ratio of absolute viscosity of the fluid at a given temperature to the absolute viscosity of a standard fluid at 20°c.

9. Define Viscosity index

It is an empirical number that indicates the effect of change of temperature on viscosity if a fluid.

10. Define fluidity.

It is the reciprocal of viscosity. It is unit is 1/ poise.

11. Define Humidity.

It is basically moisture content in air or it is the quantity of water vapour retained by gas.

12. Define Absolute Humidity.

Weight of water vapour in unit wait of gas. 1. H=Wr / Wg

13. Define Specific Humidity.

It is weight of vapors in unit weight of mixture.

14. Define Relative Humidity.

This is the ratio of moisture content of gas to maximum moisture content of the gas at that temperature.

15. Define various units of Humidity.

Vppm = parts per million / volume.

G/ kg = weight concentration

Relative humidity = in %

Dew point in Deg C.

16. Define Hygrometer.

Used to measure the moisture content in air. It also used to measure humidity.

17. What is the basic principle of Hygrometer.

It consist of mechanical device measuring the dimension change of humidity sensitive materials like animal hair, animal membrane , paper etc.

18. Define Moisture.

Defined as the amount of water absorbed by solids or liquids.

19. What are the different types of viscometer?

Say bolt viscometer Rotameter type Consistency meters.

20. What is Psychrometer?

Psychrometer is a device that uses the bulb thermometers to measure humidity. It is also used in air conditioning systems for maintaining humidity.

21. What are the different types of hygrometer?

Hair hygrometers

Wire electrode hygrometers

Electrolysis type hygrometers

Resistive type

Capacitive type

Microwave reflector

22. Explain the principle of saybolt viscometer.

As the viscosity of the fluid varies , the flow rate and hence time taken to drain the fluid through the capillary tube varies. The time indicates the viscosity and is denoted by say bolt number.

23. What is meant by consistency?

General term for viscosity and more often used in connection with Non-Newtonian fluids.

24. What is Celsius or Centigrade?

A temperature scale defined by 0°C at the ice point and 100°C at the boiling point of water at sea level.

25. Define Absolute Zero

Temperature at which thermal energy is at a minimum. Defined as 0 Kelvin, calculated to be –273.15°C or –459.67°F.

26. What is Ambient Temperature?

The average or mean temperature of the surrounding air which comes in contact with the equipment and instruments under test.

27. Define Boiling Point

The temperature at which a substance in the liquid phase transforms to the gaseous phase; commonly refers to the boiling point of water which is 100°C .

28. What is Calorie?

The quantity of thermal energy required to raise one gram of water 1°C at 15°C.

29. Define Exothermic process?

A process is said to be exothermic process when it releases heat.

30. What is Dissipation Constant?

The ratio for a thermistor which relates a change in internal power dissipation to a resultant change of body temperature.

31. What is Fahrenheit?

A temperature scale defined by 32° at the ice point and 212° at the boiling point of water at sea level.

32. Define Freezing Point

The temperature at which a substance goes from the liquid phase to the solid phase.

33. What is Kelvin?

Kelvin is the unit of absolute or thermodynamic temperature scale based upon the Celsius scale with 100 units between the ice point and boiling point of water. 0°C = 273.15K. Symbol K.

34. What is Joule?

The basic unit of thermal energy.

35. Define Heat

Heat is thermal energy. Heat is expressed in units of calories or BTU’s.

36. What is Heat Sink?

A body which can absorb thermal energy.Practicaly, A finned piece of metal used to dissipate the heat of solid state components mounted on it.

37. What is Heat Transfer

The process of thermal energy flowing from a body of high energy to a body of low energy. Transfer by Means of :conduction; the two bodies contact. Convection; a form of conduction where the two bodies in contact are of different phases, i.e. solid and gas. Radiation: all bodies emit infrared radiation.

38. What is Latent Heat?

The amount of heat needed to convert a pound of boiling water to a pound of steam.

39. State Limits of Error

A tolerance band for the thermal electric response of thermocouple wire expressed in degrees or percentage defined by ANSI specification MC-96.1 (1975).

40. What is Loop Resistance?

The total resistance of a thermocouple circuit caused by the resistance of thermocouple wire.Usually used in reference to analog pyrometers which have typical loop resistance requirements of 10 ohms.

41. What is Maximum Operating Temperature?

The maximum temperature at which an instrument can be safely operated.

42. What is Mean Temperature?

The average of the maximum and minimum temperature of a process equilibrium.

43. Define Melting Point

The temperature at which a substance transforms from a solid phase to a liquid phase.

44. What is Negative Temperature Coefficient?

A decrease in resistance with an increase in temperature.

45. Define Resistance Temperature Characteristic

A relationship between a thermistor’s resistance and the temperature.

46. What is Specific Heat?

The ratio of thermal energy required to raise the temperature of a body 1° to the thermal energy required to raise an equal mass of water 1°.

47. What is RTD?

Resistance temperature detector.

48. What is Thermal Coefficient of Resistance?

The change in resistance of a semiconductor per unit change in temperature over a specific range of temperature.

49. What is Thermal Conductivity?

The ability of a material to conduct heat in the form of thermal energy.

50. What is a Thermistor?

A temperature-sensing element composed of sintered semiconductor material which exhibits a large change in resistance proportional to a small change in temperature. Thermistors usually have negative temperature coefficients.