Sound that is perceptible by humans has frequencies from about 20 Hz to 20,000 Hz. In air at standard temperature and pressure, the corresponding wavelengths of sound waves range from 17 m to 17 mm. Sometimes speed and direction are combined as a velocity vector; wave number and direction are combined as a wave vector.
Price of a Stamp. The current price of a first class stamp is 47 cents. A domestic first class letter (1 oz.) is 47 cents. The price of each additional ounce is 21 cents. It will cost you 34 cents to send a domestic postcard.
WASHINGTON â Today, the U.S. Postal Service introduced the Global Forever First-Class Mail International stamp. Priced at $1.10 each and offered in a pane of 20, the Global stamp offers a single price for any First-Class Mail International 1-ounce letter to any country in the world.