The scales of Revati are as follows :
Aarohanam (Ascending) : S R1 M1 P N2 S’
Avarohanam (Descending) : S’ N2 P M1 R1 S
It is a Janya Raga, derived from Ratnangi (below), it is the 2nd on the Melakarta Scale.
This raga is used for chanting the Vedas and reminds us at once of religious chants. It also portrays an agonized sadness, a feeling of being bereft. Well known compositions in Revati are Nanati Baduku by Annamacharya, Mahadeva Shiva Shambho by Tanjavur Shankara Iyer and Pozhudu Miga Achchude by Ambujam Krishna. One mustn’t forget the beautiful Thillans by Lalgudi Jayaraman and Maharajapuram Santhanam..
Note : The 12 notes in the octave are named as below. Please note that C is used as Sa for the sake of simplicity as the scale is relative in Carnatic Music. Also note that the scales paint only a superficial picture of the raga as the gamakas(ornamentations) are a very important part of a raga.
Music To My Ears 
One kannada composition by poet Nissar ahmed is JOGADA SIRI describing the grandeur and ethereal beauty of world famous jog falls in karnataka. Non kannadigas should hear this sung by famous singers, preferably one with text meaning. Both tune set in Raga Revati and poem itself are superb.