Thermometry is the part of physic that deals with heat and temperature . In this blog post you will learn definitions, formulas and the basic to advance concept of thermometry to get high mark and correct more MCQ and questions in your IOE entrance exam.

Thermometry For IOE |Heat And Temperature |PHYSICS | IOE | Class 11 |PDF | MCQ | NOTE

Thermometry For IOE |PDF|

1. Heat :

It is a form of energy that changes the thermal condition of body. It flows from a body at higher temperature to a body at lower temperature.

Heat is the form of energy which provides the sensation of hotness or coldness of the object to the sense organ. • Its unit in SI system is Joule and Calorie in CGS.(1 calorie = 4.18 joule.)

2. Temperature:

• Temperature Degree of hotness or coldness of body which is determined by mean or average KE of each molecule.

• Also temperature is the thermal state of a body that determines the direction of heat flow if any two bodies are kept in contact. If two bodies are at same temperature they are said to be thermally equilibrium. Two bodies are in contact and heat is following from A to B means that A has higher temperature than that of B. We can also say that heat transfer from higher temperature of body to lower temperature of body. Its unit is oC in CGS , kelvin in SI.

Differences Between Heat and Temperature

The differences between heat and temperature can be drawn clearly on the following grounds:

1. Heat is form of energy which gives sensation of coldness and hotness. As against this, temperature is degree of hotness and coldness of the body

2. Thermal energy measures total energy of all of its molecules. On the other hand, temperature measures average kinetic energy of molecules in substance.

3. The standard unit of measurement of heat is Joules, while that of temperature is Kelvin, but it can also be measured in Celsius and Fahrenheit.

4. Calorimeter is a device, which is used to measure the heat. On the other hand, temperature can be measured by thermometer.

5. Heat is represented by ‘Q’ whereas ‘T’ is used to represent temperature.

6. Heat flow is independent of the amount of heat contained in them. While heat flows from a body at higher temperature to the body at lower temperature.

Thermal Equilibrium

The condition under which two substances in physical contact with each other exchange no heat energy. Two substances in thermal equilibrium are said to be at the same temperature.

Zeroth Law of Thermodynamics

It states that- When two systems are separately in thermal equilibrium with a third system, then these two systems are also in thermal equilibrium. Application of Zeroth law of Thermodynamics

1. Base for all the temperature measuring devices

2. Compare the temperatures of two different bodies

3. Fixed points

i. Lower fixed point : Temperature at which pure ice melt at normal pressure

ii. Upper fixed point : Temperature at which pure water boils at normal pressure .

4. Scales :

i. Celcius scale

Lower fixed point = 0^o C and upper fixed point = 100^o C

ii. Fahrenheit scale

Lower fixed point = 32^o F and upper fixed point = 212^o F

iii. Reaumer Scale

Lower fixed point = 0^o R and upper fixed point = 80^o R

iv. Absolute Scale (Kelvin)

Lower fixed point = 273^o K and upper fixed point = 373^o K

v. Rankine Scale

Lower fixed point = 492 R and upper fixed point = 672 C

Now,

$\frac{C - 0}{100 - 0} = \frac{F - 32}{212 - 32}$ $= \frac{R - 0}{80 - 0} = \frac{K - 273}{373 - 273}$ $= \frac{R n - 492}{672 - 492}$

5. Thermometers :

1. Liquid thermometers : Based on expansion of liquid on heating

A. Mercury thermometer : Mercury is used in thermometer due to

low specific heat capacity
High thermal conductivity
Unitform expansion over wide range
Can measure -32^o C to 357^o C
Does not stick on wall of tube and shining nature

B. Alcohol thermometer : It is used in cold region and high mountain where it can measure -117^o C to 78^o C

2. Gas thermometers : It is based on change in pressure at constant volume is directly proportions to change in temperature ie. Gay Lussac Law .

Most sensitive thermometers
Can measure -268^o C to 1500^o C
'He' gas is used so

$\frac{t - θ_{1}}{θ_{2} - θ_{1}} = \frac{P_{t} - P θ_{1}}{P_{θ 2} - P_{θ 1}}$

P1 = pressure at t^o C

3. resistance thermometer

It is based on variation of resistance of conductor with temperature by Rθ= Ro(1+α△θ)

➡Pure platinum is used since it has high value of temperature coefficient

➡Can measure - 200^o C to 1200^o C

Now, Formulae is here :

Rt = Resistance at t^o C

4. Thermocouple Thermometer

It is based on variation of thermo emf in thermocouple with temperature by e=Aθ+Bθ^2 ie. Seeback effect where A and B are constants whose value depends n nature of metal in thermocouple.

➡Can measure - 200^o C to 1600^o C

➡B<<A so e= Aθ

∴ formula

5. Pyrometer

i. Radiation pyrometer is based on Stefan's law of black body radiation

➡Used to measure temperature above 800^o C

➡ Cam measure the temperature of source at any distance

ii. Disappearing filament pyrometer

It is based on the filament of bulb when seen by filter disappear when its temperature is equal to distance object emitting radiation .

➡ Can measure 600^o C to 2700^o C

6. Vapour pressure thermometer

It is based on saturated vapour pressure of liquid varies temperature by :: formular

a, b, c are constant and T= Absolute temperature.

➡ Can measure 0.71K to 122 K

7. Magnetic thermometer

It is based on variation of magnetic susceptibility with temperature ( Curie Law)

➡ Used to measure temperature near about absolute zero.

Heat And Temperature :

Here is this pdf of heat and temperature. You can practice and learn from this pdf file provides below.

credit : this pdf is owner is clamphook. Visit www.clamphook.com for study material and this is the platform for preparing entrance with onlline and physical facilities.

Heat And Temperature | Thermometry For IOE | PHYSICS | IOE | Class 11 |PDF |

Thermometry For IOE |PDF|

1. Heat :