A circuit employs a silicon solar cell to detect flashes of light lasting \(0.25 \mathrm{~s}\). The smallest current the circuit can detect reliably is \(0.42 \mu \mathrm{A}\). Assuming that all photons reaching the solar cell give their energy to a charge carrier, what is the minimum power of a flash of light of wavelength \(550 \mathrm{~nm}\) that can be detected?