Author Question: When calculating the Lorenz number L classically for electrical conductivity, you arrive at an ... (Read 62 times)

jon_i

  • Hero Member
  • *****
  • Posts: 549
When calculating the Lorenz number L classically for electrical conductivity, you arrive at an answer that is proven wrong experimentally. Which of the following statements is NOT true about the quantum mechanical contribution to the value of L?
  a. Quantum mechanics provides that thermal conductivity K is proportional to electrical conductivity over Avogadro's number, /NA.
 
b. Only electrons moving near the Fermi speed will be a factor in the conductivity.
  c.Quantum mechanics predicts a larger Lorenz number than classically calculated.
  d. The quantum Lorenz number depends on a different configuration of the same physical constants that the classical number depends on.

Question 2

Which of the following is NOT a general selection rule for the filling of electron shells?
 
a. For a particular n, the subshells fill in the order s, p, d, f, ...
  b.Shielding affects the ordering of energy levels as described by n and l.
  c. The orbital and spin angular momentum in each shell and subshell are restricted by Hund's rules.
  d. Electrons usually completely fill a subshell before starting another shell.
  e. For the s shell there are 2 electrons, for the p shell 6, for the d shell 10, and for the f shell 16.



fur

  • Sr. Member
  • ****
  • Posts: 309
Answer to Question 1

This statement is not true. The thermal conductivity K is indeed directly proportional to the electrical conductivity, but it is also directly proportional to the temperature T, K
a.

Answer to Question 2

e.
This statement is not true. The f subshells each take 14 electrons. Each l value subshell can take 2(2l + 1) electrons.



Related Topics

Need homework help now?

Ask unlimited questions for free

Ask a Question
 

Did you know?

When Gabriel Fahrenheit invented the first mercury thermometer, he called "zero degrees" the lowest temperature he was able to attain with a mixture of ice and salt. For the upper point of his scale, he used 96°, which he measured as normal human body temperature (we know it to be 98.6° today because of more accurate thermometers).

Did you know?

The term bacteria was devised in the 19th century by German biologist Ferdinand Cohn. He based it on the Greek word "bakterion" meaning a small rod or staff. Cohn is considered to be the father of modern bacteriology.

Did you know?

Alzheimer's disease affects only about 10% of people older than 65 years of age. Most forms of decreased mental function and dementia are caused by disuse (letting the mind get lazy).

Did you know?

Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.

Did you know?

Though methadone is often used to treat dependency on other opioids, the drug itself can be abused. Crushing or snorting methadone can achieve the opiate "rush" desired by addicts. Improper use such as these can lead to a dangerous dependency on methadone. This drug now accounts for nearly one-third of opioid-related deaths.

For a complete list of videos, visit our video library