Determine the number of photons with wavelengths between 705 and 713 nm escaping each second from a small opening in a cavity at a temperature of 8350 K. The opening behaves like a blackbody, and has a radius of 2.20 x 10-2 mm. photons/s

The threshold of dark-adapted (scotopic) vision is 4.0 × 10−11 W/m2 at a central wavelength of 500 nm. If light with this intensity and wavelength enters the eye when the pupil is open to its maximum diameter of 8.5 mm, how many photons per second enter the eye?

b

Suppose a star with radius 8.57 × 108 m has a peak wavelength of 680 nm in the spectrum of its emitted radiation. (a) Find the energy of a photon with this wavelength. J/photon (b) What is the surface temperature of the star? K (c) At what rate is energy emitted from the star in the form of radiation? Assume the star is a blackbody (e = 1). W (d) Using the answer to part (a), estimate the rate at which photons leave the surface of the star. photons/s

c) The Bohr model of the atom postulated electrons orbiting around the nucleus in stable orbits. De Broglie explained what orbits could exist by postulating that electrons (and any- thing else) with momentum p have an associated wavelength λ, given by λ=h/p where h is Planck's constant. i) For an electron orbiting around a proton (the Bohr model), equating the centripetal force with the Coulomb force gives the expression v² = e²/(4πεmer). Calculate the speed of an electron orbiting at the Bohr radius, ˜Â = 0.053 nm. ii) Calculate the momenta and the de Broglie wavelengths of the electron of part (i) and of a bird (a racing pigeon) that weighs 0.350 kg and flies at 100 km per hour. iii) Compare the wavelength for the electron that you obtain in (ii) with the circumference of the orbit. Comment on this comparison. Explain briefly what it implies about the other possible orbits of the Bohr model and how the higher orbits might be predicted.

In a particular case of Compton scattering, a photon collides with a free electron and scatters backwards. The wavelength after the collision is exactly double the wavelength before the collision. What is the wavelength of the incident photon? (mel = 9.11 × 10-31 kg, h = 6.626 × 10-34 J ∙ s, c = 3.00 × 108 m/s) Group of answer choices 1.2 pm 4.8 pm 3.6 pm 2.4 pm

A photon having a wavelength of 182 nm strikes the surface of a metal sheet having a threshold frequency (νo) of 9.27 x 1014 s-1. Calculate the velocity of the ejected electron in SI units AND in units of miles per hour. Hint: Combine equations 1.3 (pg 16 of textbook) and 3.6 (pg. 94). Report the units of your answer.