The red wavelengths of light are the longer wavelengths and the violet wavelengths of light are the shorter wavelengths. Between red and violet, there is a continuous range or spectrum of wavelengths.
The USPS also includes that a large postcard is 49 cents to mail. The maximum size for this postcard is 11 1/2 inches long, 6 1/8 inches high and 1/4 inch thick. This is the same rate to mail a First Class 1 ounce letter domestically. The rates for postage increased as of January 2014.
Typical costs: The cost to mail a first class letter is 46 cents for up to one ounce, and each additional ounce adds 20 cents. Large envelopes (flats) that are rectangular and not too rigid or thick are 90 cents for up to one ounce (and 20 cents for each additional ounce). Expect to pay 33 cents to mail a postcard.