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.
Letters mailed first-class must be under 1 ounce to use the 49-cent stamp. If a letter is between 1 and 3.5 ounces, it costs between 70 cents and $1.12 to mail. Postcards mailed first-class cost 34 cents an ounce up to 3.5 ounces.