Physics 272: Honors Physics II
Spring 2017

# Wednesday 1 February 2017: Topics to be covered in the lecture (HRW sections 16.7, 17.1-4, 17.6)

• standing waves
• sound waves
• more on interference
• propagation of waves in two and three dimensions: wavefronts and rays
• beats

1. For the discussion of interference and standing waves, you need to review the trignometric identity sin a + sin b = 2 sin ((a+b)/2) cos((a-b)/2).
Do quizlet question 1.

2. As we will discuss in more detail in class, a string stretched between two fixed endpoints can undergo motion, called a standing wave, in which all the elements move tranaverse to the string in SHM with the same frequency, but with different amplitudes. Points at which the amplitude is zero, called nodes, are spaced at equal distances. Since the endpoints are fixed, there must be nodes at the endpoints.
Do quizlet question 2.

3. Logarithmic scales are useful to measure quantities that can vary by many orders of magnitude. Carefully read the section "The Decibel Scale" on p. 490 of the book.
Do quizlet question 3.

YOU SHOULD PREVIEW THE QUIZ QUESTIONS HERE TO BE READY TO ENTER THEM WHEN YOU START THE QUIZ IN QUIZSTAR.

Note on the quizlets: When you submit the quiz, you get a message stating how many of the questions you got right or wrong. After the first attempt, you can click "Review this Quiz" to see which questions you got wrong. After the second attempt, "Review this Quiz" will also show an arrow pointing to the right answer.