# Frequency and Amplitude

You may have noticed that a vertical gray bar is drawn on the paper at regular intervals. These gray bars are drawn every 45 degrees. They are used to help you see how fast the wave is changing. The wave’s speed is called its frequency.

You may also have noticed that the strip chart recorder has numbers at the top and bottom of the slider. These numbers show the maximum and minimum values that the slider can hit. The range of these numbers is the wave’s amplitude.

In the section below, you can select a function and enter numbers into the two fields. For example, if you put a 2 in the first field and a 4 in the second field and click the Start button, you will see the graph of 2 sin(4A), where A represents the current angle. (If you don’t put a number in the field, that is the same as a one.)

( A )

See if you can guess what will happen to the frequency and amplitude when you enter these numbers. Then enter the numbers and click Start to see if you were right.

- 2 sin(A)
- sin(2A)
- sin(0.5A)
- 2 sin(0.5A)
- 0.5 sin(2A)

Does this work the same way for cosine also? Try it and find out.