<p>A quantum ring is considered in a rotating frame in the presence of an external magnetic field. The energy levels and wave functions of the system are analytically derived by solving the Schrödinger equation. Then, an analytical expression is derived for the coefficient of direct interband light absorption (ILA). Applying the expression, the threshold frequency of absorption (TFA) is analytically derived. This frequency is calculated for different parameters such as quantum ring radius, external magnetic field, and angular frequency of the rotating frame. According to the results, we found that the system shows a frequency in petahertz (PHz) range which can be used in wireless communications, industrial manufacturing environments, disinfecting water, food, medical equipment, explosives warehouses, and underwater scenarios. The TFA in the rotating frame is higher than the frequency in the rest frame. Also, this frequency is increased by enhancing the magnetic field and QR radius.</p>