W : Build on studentsâ knowledge of literary elements by explaining how to draw conclusions, including determining the theme, based on information in folklore. H : Engage students by using the story Goldilocks and the Three Bears to model how to draw conclusions based on text.
For a signal whose fundamental frequency is f, the second harmonic has a frequency 2 f, the third harmonic has a frequency of 3 f, and so on. Let w represent the wavelength of the signal or wave in a specified medium. The second harmonic has a wavelength of w /2, the third harmonic has a wavelength of w /3, and so on.
However, the quartz and atomic clocks invented during the 1930s and 1950s are even better timekeepers, and show that the Earth does not rotate steadily but wobbles. Since 1967 the definition of the second has been related to the movement of electrons in a caesium atom: The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom.