TNPSC Free Notes Physics In English – Thermometer

இந்தக் கட்டுரையில், TNPSC குரூப் 1, குரூப் 2, குரூப் 2A, குரூப் 4 மாநிலப் போட்டித் தேர்வுகளான TNUSRB, TRB, TET, TNEB போன்றவற்றுக்கான  முறைகள் இலவசக் குறிப்புகளைப் பெறுவீர்கள்.தேர்வுக்கு தயாராவோர் இங்குள்ள பாடக்குறிப்புகளை படித்து பயன்பெற வாழ்த்துகிறோம்.

Thermometer

Thermometer- To measure temperature.
Types of thermometer:
Clinical Thermometer:
A clinical thermometer indicates temperatures from a minimum of 35°C or 94°F to a maximum
of 42°C or 108°F.
Laboratory Thermometers:
 From −10°C to 110°C
 In humans, the average internal temperature is 37°C (98.6°F)
Digital Thermometer:
Thermal readings are displayed in the Digital screen.

Scales of thermometers:
Celsius scale:
Freezing point of water 0°C to Boiling point of water 100°C.
Fahrenheit Scale:
Freezing point of water 32°F to boiling point of water 212°F.
Kelvin scale:
Freezing point of water 273K to boiling point of water 373K.
Relationship between different scales:
 (Temperature scale – Minimum value) / (maximum value – minimum value)
 (F-32)/9 = C/5
 K = 273.15 + C
Modes of heat transfer:
 Conduction
 Convection
 Radiation
Conduction:
Conduction as the process of heat transfer in solids from the region of higher temperature to the
region of lower temperature without the actual movement of atoms or molecules.

Conduction in daily life:
 We cook food in vessels made up of metals. When the vessel is heated, heat is transferred
from the metal to the food.
 When we iron dresses, heat is transferred from the iron to the cloth.
 Handles of cooking utensils are made upof plastic or wood because they are poor
conductors of heat.
 The temperature inside igloo (snow house)is warm because snow is a poor conductorof
heat.
Convection:
The form of heat transfer from places of high temperature to places of low temperature by the
actual movement of molecules is called convection. Convection takes place in liquids and gases.

Convection in daily life:
 Formation of land breeze and sea breeze is due to convection of air.
 Wind flows from one region to another region by convection.
 In hot air balloons heat is transferred by convection and so the balloon raises.
 In refrigerators, cool air moves downwardand replaces the hot air because of convection.
Radiation:
Radiation is defined as the way of heat transfer from one place to another in the form of
electromagnetic waves.

Radiation in daily life:
 Heat energy from the Sun reaches the Earth by radiation.
 While standing near fire we feel the heat which is transferred as radiation.
 Black surfaces absorb heat radiation. So that the bottom of the cooking vessels are
painted black.
 White colour reflects heat radiation. That’s why we are advised to wear white clothduring
summer.

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