A model of a standing wave

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Notice three waves: a faint grey wave moving to the left a yellow wave moving to the right a magenta wave that is the superposition of the two waves. Click on the image for a larger image (429kb)

1. How many nodes do you see?
2. How many antinodes?
3. What is the frequency of the grey and yellow waves?
4. What is the period of the magenta wave?