where \(I_{e}\) is the value of incident energy on the sample,\(P_{s}\ \)is the incident power on the sample, \(t\) is the time of exposure to radiation, \(P\) is the power of the lamp, \(A_{0}\) is the surface area of the test sample exposed to radiation, and R is the distance from the UV source to the sample [11,12]. Table 1 presents the incident energy for both exposure times, with \(R\)=5 cm and\(A_{0}\)=900 cm2.
Table. 1: Energy incident in the samples depending on the exposure time.