Advantage & disadvantages of four types of thermometry in measurement.

1. COMSATS INSTITUTEOF INFORMATION TECHNOLOGY
Identify 3 qualities and three drawbacks ofall 4 types of thermometry
Submitted To:
Sir Arbab Shahid
Submitted By:
Hafiz Khalid
SP14-BME-057
Grade: __________
Checked By: __________
Date: __________
Department of Mechanical Engineering

2. Advantages of thermal expansion:
 If we find difficult to remove the stopper from a glass bottle, we can heat the
neck of the bottle. Now the neck of the bottle expands and the stopper comes
out easily.
 The principle of thermal expansion is used in fixing iron rim with the
wooden wheel firmly.
 Rivets are used to hold steel plates together very tightly. A very hot rivet is
pushed through the two plates and its end is hammered over. When the rivets
cools down it pulls the two plates together very tightly.
 Bimetallic strip:
Disadvantages of thermal expansion:
Changing of shape and dimensions of objects suchas doors.
Wall collapsing due to bulging.
Cracking of glass tumbler due to heating and Bursting of metal pipes
carrying hot water or steam are some of the disadvantages of thermal
expansion of matter.
Advantages of Electrical Resistance:
 Electric resistance heating equipment is environmentally friendly, generating
zero greenhouse
 gases and no carbon emissions.
 Electric resistance heating is efficient becausea significant portion of
electricity is generated by hydro and nuclear facilities with the trend toward
site‐generated wind and solar power.
 Power generated by renewable sources is increasing at 1.8% per year and
trending up. Wind
 grew 10% per year for the past decade. Non‐fossil fuel power generation,
including nuclear,
 account for 28 % of the US total. The future of electric power generation is
with non‐polluting renewable energy sources.

3. Disadvantages of Electrical Resistance:
 Deep investigations require long cables and consume much field time
 Interpretation of complex geologic structures is difficult and ambiguous
 Presence of metal pipes, cables, fences and electrical grounds can
complicate interpretation.
 Accuracy of depth determination is lower than with seismic techniques
Thermal Radiation Effects And Properties:
 The chief danger of radiation is the damage it can cause to living cells.
Radiation can damage the DNA inside a cell's nucleus, and if the DNA
becomes sufficiently damaged, the cell can become cancerous. Exposure to
high amounts of radiation, or lower amounts over a long period of time, can
significantly increase the risk of developing cancer
 The characteristics of thermal radiation depend on various properties of
the surface it is emanating from, including its temperature, its
spectral absorptivity and spectral emissive power, as expressed by
Kirchhoff's law.
Thermoelectric effect: Advantageous
 It can be used to measure temperature accurately because of its
electrical nature and a wide range of temperature difference(0.001K -
2000K)
 It absorbs a very small amount of heat from the object and therefore
does not change the temperature to be measured.
 As the thermal capacity is low, it attains the temperature to be
measured quickly; this is useful in measuring changing temperatures.
 It is cheap and can be easily constructed.
 It can be used to measure temperature the of remote objects, e.g., a
furnace, and of small objects like a small cavity.

4. Disadvantageous:
 It is not a direct reading instrument, so cannot be used for calorimetric
purposes.
 For different ranges of temperature, different thermo-couples have to be
used.
 Each thermo-couple has to be calibrated individually.