Concept explainers
The spectral transmissivity of a 1-mm-thick layer of liquid water can be approximated as follows:
(a) Liquid water can exist only below its critical temperature,
(b) Determine the transmissivity of a 1-mm-thick layer of liquid water associated with melting the platinum wire used in Nukiyama’s boiling experiment, as described in Section 10.3.1.
(c) Determine the total transmissivity of a 1-mm-thick layer of liquid water exposed to solar irradiation. Assume the sun emits as a blackbody at
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Fundamentals of Heat and Mass Transfer
- 1.26 Repeat Problem 1.25 but assume that the surface of the storage vessel has an absorbance (equal to the emittance) of 0.1. Then determine the rate of evaporation of the liquid oxygen in kilograms per second and pounds per hour, assuming that convection can be neglected. The heat of vaporization of oxygen at –183°C is .arrow_forward10- In transparent materiel the greatest part is * O absorptivity are equal O reflectivity transmisivity 11-Deformation in which stress and strain are proportional is called * elastic and plastic deformation O elastic deformation O plastic deformation O visco elastic deformaticarrow_forwardA spherical radiator has a radius of 3ft and emissivity of 0.5. If radiates 6000 Btu/hr of heat at 3000R, what is the temperature of a surface affected by its radiation?arrow_forward
- A small sphere (emissivity =0.503 radius=r1) is located at the center of a spherical abestos shell ( thickness =1.74 cm, outer radius= r2; thermal conductivity of abestos is 0.090 J/ (sm c degrees) The thickness of the shell is small compared to the inner and outer radii of the shell. The temperature of the small sphere is 695 degrees Celsius while the temperature of the inner surface of the shell is 352 degrees Celsius, both temperatures remaining constant. Assuming that r2/r1 =8.75 and ignoring any air inside the shell, find the temperature in degrees Celsius of the outer surface of the shell.arrow_forwardThe strongest colors reflected in a thin film have wavelengths in the film equal to of the thinnest possible film. a. the thickness b. twice the thickness c. four times the thickness d. two or four times the thickness, depending upon the number of wave inversions In a double-slit experiment, the slits are 0.025 mm apart and a screen is placed 0.75 m away. The first order bright band is found to be 1.35 cm from the central bright band. What is the wavelength of the light? a. 250 nm b. 410 nm c. 450 nm d 720 pmarrow_forwardA furnace with an aperture of 30 mm diameter and emissive power of 4x10^5 W/m^2 is used to calibrate a heat flux gage having a sensitive area of 2x10^-5 m^2At what distance, measured along a normal from the aperture, should the gage be positioned to receive irradiation of 1000 W/m^2 ? If the gage is tilted off normal by 20^o what will be its irradiation?arrow_forward
- Solve fastarrow_forwardYou can neglect radiation at the bottom of the plate; the bottom side of the plate has water flowing underneath it. Often, when dealing with liquids (rather than gases), one can neglect radiation because heat transfer due to convection is so much larger (liquids tend to have higher convection coefficient values than gases).arrow_forwardA small sphere (emissivity = 0.745, radius = r1) is located at the center of a spherical asbestos shell (thickness = 1.72 cm, outer radius = r2; thermal conductivity of asbestos is 0.090 J/(s m Co)). The thickness of the shell is small compared to the inner and outer radii of the shell. The temperature of the small sphere is 727 °C, while the temperature of the inner surface of the shell is 406 °C, both temperatures remaining constant. Assuming that r2/r1 = 6.54 and ignoring any air inside the shell, find the temperature in degrees Celsius of the outer surface of the shell.arrow_forward
- Consider an ideal gas enclosed in a spectral tube. When a high voltage is placed across the tube, many atoms are excited, and all excited atoms emit electromagnetic radiation at characteristic frequencies. According to the Doppler effect, the frequencies observed in the laboratory depend on the velocity of the emitting atom. The nonrelativistic Doppler shift of radiation emitted in the x direction is f = f0(1 + vx / c). The resulting wavelengths observed in the spectroscope are spread to higher and lower values because of the (respectively) lower and higher frequencies, corresponding to negative and positive values of vx. We say that the spectral line has been Doppler broadened. This is what allows us to see the lines easily in the spectroscope, because the Heisenberg uncertainty principle does not cause signifi cant line broadening in atomic transitions. (a) What is the mean frequency of the radiation observed in the spectroscope? (b) To get an idea of how much the spectral line is…arrow_forwardPlanck's radiation law is given as: 8thv³ I = n(v)ɛ =- c3 hv ekBT – 1 8nhc 1 = n(1)ē = 25 hc eAkgT – 1 (a) Show that it reduces to the Rayleigh-Jeans law as 2 –∞. (b) Show that it reduces to Wien's law in the short wavelength limit (1 → 0). Evaluate a and b. (c) Derive the constant in the Wien's displacement law.arrow_forwardAnalysis 3: Based on the design of the antennas, the Standard Absorption Rate (SAR) of RF power by the patient tissue is expected to be as follows: SAR(t) = 2t + e0.1t+2 where, t is time in seconds. 2. Plot the SAR function for the first 80 seconds.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning