Number of photons emitted each second by a 100 W light bulb?

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Photons released by nuclear decays tend to be in the MeV range, and atomic nuclei are a few femtometers (10-15 m) across. If a single proton trapped in an inescapable rectangular box releases a 1.3 MeV photon when dropping from the n = 2 to the n = 1 state, how wide is the box, in femtometers? You should find that this quick and dirty estimate is remarkably close to the real size of a nucleus! The proton mass is about 1.7 x 10-27 kg. 1 MeV = 1.6 x 10-13 J. Planck's constant is approximately h = 6.6 x 10-34 J s.

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Chapter 10, Problem 4C

To determine

Number of photons emitted each second by a 100 W light bulb?

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Photons released by nuclear decays tend to be in the MeV range, and atomic nuclei are a few femtometers (10-15 m) across. If a single proton trapped in an inescapable rectangular box releases a 1.3 MeV photon when dropping from the n = 2 to the n = 1 state, how wide is the box, in femtometers? You should find that this quick and dirty estimate is remarkably close to the real size of a nucleus! The proton mass is about 1.7 x 10-27 kg. 1 MeV = 1.6 x 10-13 J. Planck's constant is approximately h = 6.6 x 10-34 J s.

You are asked to design a spectral filter that practically removes 99.0% of the low energy photons in an X-ray beam. Such photons contribute to the patient dose without contributing to the image and are defined as no more than 1% of these photons making it to the other side of the patient. Assume a patient can be modelled as a 20cm thick homogenous object with linear attenuation coefficients as shown below in Table 1. What is the thickness of the filter needed to eliminate all the energies which satisfy the above requirement? Filter linear attenuation properties are given below in Table 2. Table 1: Linear attenuation coefficients vs. energy of patient equivalent material Energy [keV] Habject (mm| 20 0.02601 30 0.02407 40 0.02303 50 60 0.02151 0.02013 Table 2: Linear attenuation coefficients vs. energy of filter material 60 0.06684 20 Energy (keV] Hrter (mm 30 40 50 70 0.1225 0.1067 0.0872 0.07541 0.06327

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