1. a = b/2 =g /3 Where a , b, g are coefficient of linear , superficial and cubical expansion resp.
2. specific heat is
max for H2
Min for actinium and radon
3.dulong and petit rule :
atomic wt. * specific heat = constant
4. two bodies at different temperature T1 and T2 , if brought in thermal contact do not necessarily settle to mean temperature .
the final temp = mean temp only when thermal capacities of bodies are equal.
5.for ideal gas internal energy depends only on temperature
6. for real gas , internal energy depends on temp and vol.
7. slope of adiabatic curve = g times the slope of isothermal curve
as g > 1 , adiabatic curve at any point is steeper than isothermal curve at that point.
8.no work is done on / by the gas during isochoric process . heat absorbed by gas goes entirely to change its internal energy.
9. at any point in front of fire , heat is due to radiation
at any point above the fire , heat is due to radiation and convection.
10. TC -0 / 100 = TF - 32 /180 WHERE . TC is temp in celcius and TF is temp in Fahrenheit.
11. article of black will cool the earliest . black surfaces are good absorbers and hence good emitters.
12. on increasing the pressure , m.p of ice decreases but m.p of wax increases.
13. a large iceberg melts at the base but not at top due to high pressure ice at base , lowers its m.p
14 . snow on mountains do not melt all at once when it is heated by sun bcoz it has high latent heat of fusion. ( very confusing..... I never understood this....)
15.efficiency of carnot engine is independent of the nature of working substance .
16. internal energy of compressed gas is less than that of a rarefied gas at the same temperature . here K.E is same but during compression , molecules come close and attraction between molecules increases . P.E is added to the internal energy . as potential energy is negative , so total energy of compressed gas decreases .
16 . if hot air rises up , why is it cooler at top of hills....????
pressure decreases with height . when hot air rises it suffers adiabatic expansion.
del Q = del U + del W
0 =del U + del W
this causes decrease in internal energy and so the temp. falls
17 .a thermostat bottle containing coffee is vigourously shaken...then...
1. temp of coffee rises
2. heat is not added since bottle is thermally insulated
3. work is done on it . its delta U is +ve .
18.efficiency of a carnot engine working between ice point and steam point is 26.81 %
19 . area under a curve in a P-V diagram represents workdone on/by the system
area inside a closed curve in a P-V diagram represents work done in a cyclic process.
20. r m s speed of molecules depend only on temp .
21.the bulb of 1 thermometer is spherical while the other is cylindrical .Both hav equal amt of Hg . cylindrical bulb thermometer will respond quickly to temp as it has greater surface area.
22. . there r 2 spheres of same material- 1 hollow and 1 solid. if they r heated to same temp , the expansion of both are equal.
23.. sun's temp is measured using pyrometer.
24.a metallic ball has spherical cavity at its centre . if the ball is heated, vol . of cavity decreases due to inward expansion.
25. newton's law of cooling is used to find specific heat of liquids in labs.
26 . newton's law is a law of cooling by convection whereas stefan's law give sthe heat given out by a body due to radiation.
Hope it proves to be useful.....
plzzzzz post ur comments...!!!
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