In astronomical observations, signals observed from the distant stars are generally weak. If the photons detector receives a total of `3.15 xx 10^-18` J from the radiations of 600 nm, Calculate the number of photons by the detector.

Lifetimes 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.

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

Monochromatic electromagnetic radiation from a distant source passes through a slit.The diffraction pattern is observed on the screen 2.5 m from the slit. If the width of the central maximum is 6.00 mm, what is the slit width if the wavelength is:- 500 nm (visible light)

Monochromatic electromagnetic radiation with wavelength from a distant source passes through a slit. The diffraction pattern is observed on a screen 2.50 m from the slit. If the width of the central maximum is 6.00 mm, what is the slit width if the wavelength is (a) 500 nm (visible light); (b) 50.0 um (infrared radiation); (c) 0.500 nm (x rays)?

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

An ideal gas expands from a volume of 5dm3 to 15dm3against a constant external pressure of 2.025 xx 10^5Nm^(-2) . Find DeltaH if Deltau is 410J.

Calculate the number of photons of wavelength 6.63 mm emerging every second from a maser whose output is 6 xx10^-8 W .

The photoelectric threshold wavelength of a metal is 230 nm. Determine the maximum kinetic energy in joule and eV of the ejected electron from metal surface when it is exposed to a radiation of wavelength 180 nm. (Planck's constant h = 6.63 xx 10^-34 J-S, C = 3 xx 10^8 m//sec .)