To simply use the word "light" to describe Deepti is quite incorrect.

Deepti is the ray of light that gives renewed hope when all is lost. It's used in Hindi prose to describe situations during the Indian freedom struggle and such. An general example (as related by my mother) would be : A man lost in the woods and as night sets in he is frightened, hear wild animal sounds and is hungry and tired. Just as he resigns himself to his eventual fate of death(all hope is lost), a ray of light filters in through the heavily wooded trees. It's a small lamp lit in a small hut. The ray of light and the associated rush of hope and relief that fills the tired man's heart is "Deepti".