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Properties Of Matter
Others
Heat Capacity
Heat Capacity of a body "C": - Is the amount of heat required to raise the temperature of a body by 10 C or 1 K. Unit of C is J/k or J/0C.
Specific heat capacity "c":-
The amount of hear required to produce unit temperature in unit mass of the substance. Unit of C is J/kgK or J/kg0C. OR
It is the amount of heat required to raise the temperature of 1 kg of a body by 10C ( i.e.: 1 K ).
Thus C = mc.
The amount of heat ∆Q added to a body of mass m to raise its temperature by ∆θ is given by "∆Q = mc∆θ", c is the specific heat capacity of the body.
Latent Heat
Latent heat is the heat needed to change the state of a substance. The temperature is constant for both states. This happens only at the boiling point (b.p) and the freezing point. This is why the heat is latent i.e.: hidden.
Latent heat of vaporization of a liquid:- The amount of heat required to change the liquid at b.p to vapour at the same temperature ( i.e.: boiling point )
Specific Latent heat of Vaporization Lv:- Is the heat required to convert unit mass of the liquid at its boiling point into vapour at the same temperature.
Specific Latent heat of Fusion Lf:- The specific latent heat of fusion of a solid is the heat required to convert unit mass of it, at its melting point (m.p), to liquid at the same temperature.
Latent heat of fusion L = mLf, where m is the mass.
Latent heat of vaporization L = mLv, where m is the mass.
The heat is transferred to the system to change its state or to raise its temperature can be supplied by an electric heater. This heat ( ∆Q ) = Pt,
P = the power of the heater.
t = the time in which the heater is used to achieve the above mentioned process.
∆Q = Pt = IVt OR ∆Q = IVt = mL OR ∆Q = IVt = mc∆θ
Black body radiation & temperature
Every blackbody gives off different amounts of different wave lengths depending on its temperature. The colour of the body depends on the wave length which have the maximum intensity. This is, in its turn, dependent on the temperature.
For our sun, the peak ( maximum intensity ) is in the middle of the visible spectrum, so it looks yellow-white. Other stars ( suns ) look different because they are hotter. [ e.g.: Procyon is a blue star ]. [ Temperature of our sun is about 6000 K while that of Procyon is 8000 K ].