What is the most accurate physical analog for a particle in a ...

[theo]

What is the most accurate physical analog for a particle in a box?
  a. A guitar string
  b. A rope driven with a sinusoidal oscillation on one end and fixed on the other end
  c. A pan-flute pipe (open on both ends)
  d. An organ pipe open on only one end
  e. A jump rope with a girl on each end driving the end to a rhythm

Question 2

Which of the following statements is NOT true about the expectation value of a physical observable?
 

 

a. It is calculated from wave functions.
  b. It is usually near in agreement with experimental results.
  c. It can be calculated for energy, momentum, and position.
  d. It is best described as a probable average of many measurements.
  e. It can only be found after normalizing the wave functions involved.

 

[hanadaa]

Answer to Question 1

a.
A particle in a box should be described by a wave function that shows a probability approaching zero at both ends of the box with a ground state maximum at the center. A guitar string is fixed on both ends and cannot vibrate at the ends, but does so at a maximum amplitude in the center.

Answer to Question 2

e.
This statement is not true. To find the expectation value for a physical observable, it is much like taking the average of a series of measurements, except that this series of measurements is a function given by the wave function. The average is the function values times the weight (the x-values) divided by the summed total of the function values. Normalization is not necessary in this case. The summed total of the probability function should be 1 when normalized, but the expectation value can use the summed total of the probability function even if it is not normalized.

[theo]

Gracias!

[bdobbins]

TYSM