Week 9 Non Zero Temperature Properties of Solids

Question 1

what is the heat capacity definition equation

Answer 1

C = dQ/dT

Question 2

what is the Dulong Petit Law

Answer 2

Around 50% of solid monoatomic elements have a molar heat capacity

Question 3

what is the equipartition principle

Answer 3

average energy in each accessible degree of freedom of a system is in thermal equilibrium with kT/2

Question 4

what is the classical heat capacity equation and what is its problem

Answer 4

C = 3R

Breaks down at low temperatures

Question 5

what is the Einstein model and its equation

Answer 5

Assumes atoms vibrate independently as QHO in each direction so have same energy
E = (nx+ny+nz+3/2)ħω

Question 6

what is the Einstein temperature equation

Answer 6

θE = ħω/k

Question 7

what is the important quantum correction made by the Einstein model

Answer 7

when T < θE many excitation states are accessible so heat capacity reduces

Question 8

what is the Distribution function equation

Answer 8

D(E,T) = g(E)f(E,T)

Question 9

what is the problem with the Einstein model

Answer 9

at extremely low temperatures T –> 0 Einstein predicts an exponential model whereas as T^3 model is observed instead

Question 10

what is the idea of the Debye model

Answer 10

there is no maximum or minimum phonon energy

Question 11

how does occupancy change as temperature increases

Answer 11

as temperature increases the guarantee that a state will be occupied disappears

Question 12

what is the total heat capacity equation

Answer 12

Ctot = Ce + Cphonon = γT + αT^3