What are the advantages and disadvantages of classical free electron theory of metals?

Classical free electron theory was proposed by Drude .According to this there are some merits

1)It varifies ohm's law

2)It explains the electrical and thermal conductivities of metals.

3)It derives Weid man-franz law.

$)it explains optical properties of metal.

Demerits:-

1)The phenomena such as photoelectric effect,compton effect and the black body radiation could not be explained.

etc...

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