Heat Flashcards
Effects of heat
Expansion
Change in state
Change in temperature
Chemical changes
We wear woolen clothes in winter to keep ourself warm
Air, Which is the bad conductor does not allow our body heat to escape
Mercurys used in thermometer
Is a good conductor of heat
The process of transfer of heat in solids from origin of higher temperature to region lower temperature without the actual moment of molecules called
Conduction
The flow of heat through a fluid from places of higher temperature to place of lower temperature by a movement of fluid itself
Convection
Examples of convention in daily life
1 Hot air balloon
2 breeze (land breeze and sea breeze)
3 wind
4 chimney
Radiation is the flow of heat from one place to another by means of _______
Electromagnetic waves
Radiation is limited by all bodies above
0K
We can observe all the 3 ways of heat transfer
Wiring wood
White or light coloured crackers are good reflector of heat
They keep us cool during summer
Base of cooking utensils is blackened
Because black surface observe more heat from the surroundings
Surface of airplanes highly polished
Because it help to reflect most of the heat radiation from the Sun
_____ is there degree of hotness or coldness of the body
Temperature
Kelvin scale is also known as
Absolute scale
Fahrenheit scale
32-212°F
Celsius scale
0-100°C
Formula for convertian Celsius scale to fahrenheit scale
F=9/5C+32
C=5/9(F-32)
Temperature at which is the molecules of a substance have thier lowest possible energy
0K
SI unit of temperature
Kelvin
The solid liquid gases faces of water can co exist in equilibrium at
273.16K
Kelvin is defined as
1/273.16 of the triple point of temperature
If Fahrenheit scale is 0°F then Kelvin and Celsius scale will be
-18°C and 255K
Vice versa
If Fahrenheit scale is 32°F then Kelvin and Celsius scale will be
0°C and 273.15K
If Fahrenheit scale is 212°F then Kelvin and Celsius scale will be
100°C and 373.15 K
If Fahrenheit scale is -460°F then Kelvin and Celsius scale will be
-273°C and 0 K
The temperature at which the pressure and volume of a gas theoretically reaches 0 is called
Absolute zero
For all gases the pressure extrapolates to zero at the temperature -273.15°C. it is known as absolute zero or 0 K
Temperature of boiling point of water
373.15 K
100°C
212°F
Temperature of melting point of ice
273.15 K
0°C
32°F
Absolute zero
0 K
-273 °C
-460 ° F
Convert celcius to kelvin
K= C + 273.15
The amount of heat energy observed or lost by a body is determined by 3 factor
1 Mass of the body
2 change in temperature of the body 3 natural the material of the body
Formulas specific heat capacity
C. = Q
————
m ∆T
T change in temperature
M mass of the body
Q quantity of heat obsorbed
The SI unit of specific heat capacity
J kg^-1 K^-1
The amount of heat required to the raise the temperature of 1 kg of the substance by 1 degree Celsius or 1K
Specific heat capacity
________ has the highest specific heat capacity and its values ______
Water
4200 J/kg K
Water absorbs large amount of heat for unit raise in temperature
Water is used as a coolant in car radiators and factories to keep engine and other machinery parts cool
Water in its various form as different specific heat capacity
Water 4200 J/ (kg K)
ice. 2100 J /(kg K)
stream. 460 J/(kg K)
Heat capacity or thermal capacity
Is defined as the amount of heat energy required to raise the temperature of body by 1 degree Celsius
C’ =Q/T
S.I unit of heat capacity
J/K
The case of water melting and boiling occurred at
0°C
The process in which year solid is converted to liquid by obsorbing heat is called
Melting or fusion
Boiling point as well as condensation point of water is
100°C
The process in which a solid is converted to gas state is called
Sublimation
The amount of heat energy observed or released by a substance during a change in its physical States without any change in its temperature
Latent heat
Latent heat of fusion
heat energy is absorbed by the solid during melting and an amount of heat energy is liberated by the liquid from during freezing without any temperature change
Latent heat of vaporization
Heat energy is observed by a liquid during vaporization and equal amount of heat energy is liberated by the vapour during condensation without any temperature change
Specific latent heat
Amount of heat energy observed or liberated by unit mass of a substance during change of state without causing any change in temperature
L=Q /m
SI unit of specific latent heat is
J/kg
Convection take place in _______ and conduction take place in _______
Liquid and gas
Solid
Calories the unit of
Heat
Two cylindrical rod of same length how the area of cross section in the ratio 2:1 if both the material made up of same material which of them conduct heat faster
a) both rod b) rod 2
c) rod 1. d) none
Rod 1
Your device in which season loss of heat due to conduction convection and radiation is minimised is
Thermos flask
The fastest mode of heat transfer is
Radiation
Liquid and gases are generally _____ conductor of heat
Poor
The fixed temperature at which matter changes state from solid to liquid is called
Melting point
