A sound with a frequency of 25 kHz is in the ______________ ...

[theo]

A sound with a frequency of 25 kHz is in the ______________ region of the sound spectrum.
 a. infrasonic
  b. ultrasonic
  c. audible
  d. visible

Question 2

An energy band in a solid consists of
 a. an infinite number of levels, with each level corresponding to a point in a box.
  b. a large number of energy levels so closely spaced that they may be regarded as a continuous band.
  c. an infinite number of wave functions, with each wave function corresponding to a point in a box.
  d. a large number of electrons so closely spaced that they may be regarded as a continuous band of electric charge.
  e. an infinite number of electrons, with each electron corresponding to a point in a box.

[Amiracle]

Answer to Question 1

b

Answer to Question 2

b

[theo]

Thank you!

[Amiracle]

Always glad to help...