Hawking radiation from not-extremal and extremal Reissner-Nordstrom black holes

We consider the non-extremal Reissner-Nordstrom black hole and construct a wave packet that exhibits the Hawking radiation. We find the average of the number of the created particles with respect to the $\mathrm{\mid }0⟩$ vacuum state and with respect to Unruh type vacuum state. The average of the number operator in the $\mathrm{\mid }0⟩$ vacuum state consists of two terms: one is related to the Hawking radiation and the second is not related. We use the same construction for the extremal RN black hole and get that the average of the number operator with respect to the $\mathrm{\mid }0⟩$ vacuum state is also a sum of two term, where the one related to the Hawking radiation is equal to zero. This result is consistent with other works on the Hawking radiation for the extremal RN black hole.