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classes:2009:fall:phys4101.001:q_a_1023

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Oct 23 (Fri) Quiz 2

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Schrodinger's Dog

What is the difference between Dirac's delta function and the Kronecker delta function?

Dark Helmet 10/22

It seems to me they are related only in name. The Kronecker delta is just a function of two variables that is 1 if they are equal and 0 if they are not. The Dirac delta function is a mathmatical construct to help us solve some problems

Mercury 10/23/09 8:00am

To expand on Dark Helmet's answer, the Dirac delta function is a function that is zero everywhere except at δ(0), where it is infinite. The integral of a Dirac delta function is always 1 (provided that the integral includes δ(0)). The Kronecker delta is most useful when defining orthonormality–whenever m≠n, the inner product of two eigenfunctions is zero; whenever m=n, the inner product is 1 (provided the functions are normalized).

Mercury 10/23/09 8:05am

What is a determinate state?

Devlin 10/23 830a

 As far as I can tell, determinate states are just eigenfunctions of certain operators.  For example, the stationary states we've been studying are determinate states of the Hamiltonian.  For the stationary states, every measurement of the particle in a stationary state gives a corresponding energy.  It really is just eigenfunctions and eigenvalues.

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classes/2009/fall/phys4101.001/q_a_1023.1256305558.txt.gz · Last modified: 2009/10/23 08:45 by x500_bast0052