Chapter Questions
What voltage must be applied to a tungsten filament to produce a continuous spectrum of X-rays having a minimum wavelength of 0.09 nn ?
A tungsten filament is heated with a 12400 V power supply. What is(a) the wavelength and(b) frequency of the highest-energy X-rays that are produced?
What is the minimum voltage required to produce $K_a \mathrm{X}$-rays in nickel?
Based on the charactetistic X-rays that are embted, determine the difference in energy between electrons in(a) the $K$ and $I$, shells,(b) the $K$ and $M$ shells, and(c) the $L$ and $M$ shells of tungsten.
Pigure 20.21 shows the results of an X-ray fluorescent analysis, in which the energy of $X$ rays emitted from a material are ploted relative to the wavelength of the X-rays. Determine(a) the accelerating voltage nsed to produce the exciting X -rays and(b) the identity of the elemens in the sample.
Pigure 20.22 shows the energies of X-rays produced from an energy-dispersive analysis of tadiation enitted from a specimen in a scanthing electron ulicroscope. Determine the identity of the elements lu the sanuple.(FIGURE CAN'T COPY)
$ \mathrm{CaWO}_4$ has a relaxation time of $4 \times 10^{-6} \mathrm{~s}$. Determine the time required for the intensity of this phosphorescent material to decrease to $1 \%$ of the original intensity after the stimulus is removed.
The Intensity of a phosphorescent material is reduced to $90 \%$ of its original intensity after $1.95 \times 10^{-7} 5$. Determine the time required for the intensity to decrease to $1 \%$ of its original intensity.
By appropriately doping yttrium aluminium gamet with neodymium, electrons are excited within the $4 f$ energy shell of the Nd atoms. Detemnine the approxinate energy Iransition if the Nd: YAG serves as a laser, producing a wavelength of 532 nm . What colour would the laser beam possess?
Determine whether an incident beam of photons with a wavelength of 750 nm will cause luminescence in the following materials (see Table 18.8):(a) ZnO(b) GaP(c) GaAs(d) GaSb(e) PbS
Determine the wavelength of photons produced when electrons excited into the conduction band of indium-doped silicon(a) drop from the conduction band to the acceptor band and(b) then drop from the acceptor band to the valence band (sce Table 18.7).
Which. if any, of the semiconducting compounds listed in Table 18.8 are capable of producing an infrared laser beam?
What type of electromagnetic radjation (ultraviolet, infrared, visible) is produced from(a) pure germanium and(a) germanium doped with phosphorus? (See Tables 18.6 and 18.7.)
Which, if any, of the dielectric materials listed in Table 18.9 would reduce the speed of light in air from $3 \times 10^8 \mathrm{~m}^{-1}$ to less than $0.5 \times$ $10^3 \mathrm{~m}, \mathrm{~s}^{-1}$ ?
A beam of photons strikes a material at an angle of $25^{\circ}$ to the normal of the surface. Which, if any, of the materials listed in Table 20.2 could cause the beam of photons to continue at an angle of 18 to $20^{\circ}$ from the nomal of the material's surface?
A laser beam passing through air strikes a 50 mm -thick polystyrene block at a $20^{\circ}$ angle to the normal of the block. By what distance is the beam displaced from its original path when the beam reaches the opposise side of the block?
A beam of photons in alt strikes a composite material consisting of a $10-\mathrm{mm}$ thick sheet of polyethylene and a $20-\mathrm{mm}$ thick sheet of soda-lime glass. The incident beam is $10^{\circ}$ from the normal of the composite. Determine the angle of the beam with respect to the normal as the beam(a) passes through the polyethylene,(b) passes through the glass, and(c) passes through air on the opposite side of the composite.(d) By what distance is the beam displaced from its original path when it emerges from the composite?
A glass fibre ( $n=1.5$ ) is coated whith PTPE, Calculate the maximum angle that a beam of light can deviate from the axis of the fibre without escaping from the inticr portion of the fibre.
A material has a linear absorfition coefficient of $5.91 \times 10^4 \mathrm{~m}^{-1}$ for photons of a particular wavelength. Deteronine the thickness of the material required to absorb $99.9 \%$ of the photous.
What filter material would you use to isolate the $K_\alpha$ peak of the following X-rays: iron, manganese, nickel? Explain your answer.
A bearn of photons passes through air and strikes a soda-lime glass that is part of an aquarium containing water. What fraction of the beam is reflected by the front face of the glass? What fraction of the remaining beam is reflected by the back face of the glass?
We find that $20 \%$ of the original intensity of a beam of photons is transmithed from air through a 10 mm -thick material having a dielectric constant of 2.3 and back into air. Determite the fraction of the beam that is(a) refiected at the front surface,(t) absorbed in the material, and(c) reflected at the back surface.(d) Determine the linear absorption coefficient of the photons in the material.
Figure 20.23 shows the inensity of the radiation obtained from a copper X-ray generating tube as a function of waveleligth. The accottpanying table shows the lineas absorption coefficient for a nickel filter for several wavelengths. If the Ni fitter is 0.05 n m thick, calculate and plot the itstensity of the transmitted $X$-ray beam versus wavelength.(FIGURE CAN'T COPY)
Nickel X-tays are to be generated inside a container, with the X -rays being emitted from the container through only a small slot. Design a container that will ensure that no more than $0.01 \%$ of the $K_{\text {e }}$ nickel X-rays escape through the rest of the container walls, yet $95 \%$ of the $K_{\mathrm{a}}$ nickel X-rays pass through a thin window covering the slot. The following data give the mass absorption coefficients of several metals for nicket $\kappa_a \mathrm{X}$-rays. The mass absorption coefficient $\mu_{\mathrm{so}}$ is $\mu / \rho$, whete $\mu$ is the linear mass absorption coefficient and $\rho$ is the density of the filter material.(FIGURE CAN'T COPY)
Design a niethod by which a photoconductive material be used to measure the temperature of a material from the material's thermal emission.
Design a metbod, based on a material's refractive characteristics, that will cause a beam of pliotons originally at a $2^{\circ}$ angle to the normal to the material to be displaced from its origisal path by 20 mm at a distance of 500 mm from the material.
Design a 900 mm diameter satellite housing an infrared detector that can be placed fato a low Earth orble and that will not be delected by radar.