In astronomical observations, signals observed from the distant stars are generally weak. If the photon detector receives a total of '3.(15) xx 10^(-18) J' from the radiations of '600 nm', calculate the number of photons received by the detector.

Nitrogen laser produces a radiation at a wavelength of 337.1 nm. If the number of photons emitted is 5.6 xx 10^(24) per second, calculate the power of this laser.

Life of the molecules in the excited states are often measured by using pulsed radiation source of duration nearly in the nano second range. If the radiation source has the duration of 2 ns and the number of photons emitted during the pulse source is '2.5 xx 10^(15)', calculate the energy of the source.

Emission transitions in the Paschen series end at orbit n=3 and start from orbit n and can be represented as v=3.29 xx 10^(15) (H z) [1 / 3^2-1/ n^2] : Calculate the yalue of 'n' if the transition is observed at 1285nm. Find the region of the spectrum.