Remember from Lesson 3 that a beat is the throbbing variation in the loudness of sound caused by interference when two tones of slightly different frequencies are sounded together.  To find the beat frequency, you just need to subtract the two individual frequencies.  It doesn't matter which frequency is A or B because you are taking the absolute value of the difference.

Click here for the paper that I use in the video.  As you watch this video, pause it and try the math on your own.  When you have your answer, start the video and see if you are right.  It is important to know where YOU make your mistakes so you can correct them for next time!

Remember there are more practice math problems under Chapter 15 Resources.  Practice the math and see if your answer matches my answer.

Click on the picture to take you to the practice problems that I will be going over the next time we have class.  Remember, you need to try the problems on your own to see where you make your mistakes if you want to learn how to do the math problems on your own.

Click on the picture to take you to the abbreviations and units that we will need to know for chapter 15.  I will be reviewing these in class.  Be sure that you know all of these before the math assessment!

Is 45 minutes really the longest anyone can stay in a perfectly silent, pitch-black room?  Click on the video to see a neat video on an anechoic chamber.  An anechoic chamber is a room designed to completely absorb reflections of either sound or electromagnetic waves.  They are often isolated from waves entering from their surroundings. 

Be sure to head over to google classroom and fill out the exit pass.