27.1 Black Body
* EST Estimate the surface area of a 60-watt lightbulb filament. Assume that the surface temperature of the filament when it is plugged into an outlet of 120 V is about 3000 K and the power rating of the bulb is the electric energy it consumes (not what it radiates). Incandescent lightbulbs usually radiate in visible light about 10% of the electric energy that they consume.
Want to see the full answer?
Check out a sample textbook solutionChapter 27 Solutions
Pearson eText for College Physics: Explore and Apply -- Instant Access (Pearson+)
Additional Science Textbook Solutions
Essential University Physics (3rd Edition)
Sears And Zemansky's University Physics With Modern Physics
Essential University Physics: Volume 1 (3rd Edition)
Conceptual Physics (12th Edition)
Essential University Physics: Volume 2 (3rd Edition)
Life in the Universe (4th Edition)
- Ultraviolet (UV) radiation is a part of the electromagnetic spectrum that reaches the Earth from the Sun. It has wave-lengths shorter than those of visible light, making it invisible to the naked eye. These wavelengths are classified as UVA, UVB, or UVC, with UVA the longest of the three at 320 nm to 400 nm. Both the U.S. Department of Health and Human Services and the World Health Organization have identified UV as a proven human carcinogen. Many experts believe that, especially for fair-skinned people, UV radiation frequently plays a key role in melanoma, the deadliest form of skin cancer, which kills more than 8000 Americans each year. UVB has a wave-length between 280 nm and 320 nm. Determine the frequency ranges of UVA and UVB.arrow_forwardSuppose a star 1000 times brighter than our Sun (that is, emitting 1000 times the power) suddenly goes supernova. Using data from Table 7.3: (a) By what factor does its power output increase? (b) How many times brighter than our entire Milky Way galaxy is the supernova? (c) Based on your answers, discuss whether it should be possible to observe supernovas in distant galaxies. Note that there are on the order of 1011 observable galaxies, the average brightness of which is somewhat less than our own galaxy.arrow_forward(a) Calculate the wavelength of a photon that has the same momentum as a proton moving at 1.00% of the speed of light. (b) What is the energy of the photon in MeV? (c) What is the kinetic energy of the proton in MeV?arrow_forward
- (a) What is the wavelength of a 1.00-eV photon? (b) Find its frequency in hertz. (c) Identify the type of EM radiation.arrow_forwardA 900-W microwave generator in an oven generates energy quanta of frequency 2560 MHz. (a) How many energy quanta does it emit per second? (b) How many energy quanta must be absorbed by a pasta dish placed in the radiation cavity to increase its temperature by 45.0 K? Assume that the dish has a mass of 0.5 kg and that its specific heat is 0.9 kcal/kg • K. (c) Assume that all energy quanta emitted by the generator are absorbed by the pasta dish. How long must we wait until the dish in (b) is ready?arrow_forwardWhat is the essential difference between gamma rays and green light? A. Gamma rays have an electric field, green light do not. B. There is no essential difference in the nature of gamma rays and green light other than he difference in frequency and wavelength. C. Greenlight undergoes refraction, gamma rays I do not D. Gamma rays are a form of radiation, green light is not E. Greenlight is the beam of photons, gamma rays are not photonsarrow_forward
- The blackbody radiation emitted from a furnace peaks at a wavelength of 6.4 x 10-°m (0.0000064 m). What is the temperature inside the furnace? Karrow_forwardWhich of the following statements about a black body are true? Select one or more: a.The spectrum of the cosmic background radiation corresponds with great accuracy to the radiation of a black body at a temperature of 2.7 K. b.A black body absorbs all the radiation that hits it, and emits no radiation at all. c.According to Planck's radiation law (black body distribution), the wavelength corresponding to the maximum energy density of the radiation decreases (and the frequency increases) as the temperature increases. d.A black body reflects all the radiation that hits it, and absorbs no radiation at all.arrow_forwardWhich of the following statements about a black body are true? Select one or more: a. The spectrum of the cosmic background radiation corresponds with great accuracy to the radiation of a black body at a temperature of 2.7 K. b. A black body absorbs all the radiation that hits it, and emits no radiation at all. C. According to Planck's radiation law (black body distribution), the wavelength corresponding to the maximum energy density of the radiation decreases (and the frequency increases) as the temperature increases. d. A black body reflects all the radiation that hits it, and absorbs no radiation at all.arrow_forward
- Can any of these be classified as visible radiation? Determine the optimal course of action. t) Put up a sign at the office bulletin board proclaiming your success to the staff. By posting important guidelines on a digital whiteboard, employees may be certain that they are up-to-date on the laws and regulations that affect them. Keep your employees up-to-date on the latest happenings by posting information on digital displays or whiteboards. Abovearrow_forward3. Dimensional analysis can provide insight into Stefan-Boltzmann's law for the radiation from a black body. According to this law the intensity of radiation, in units of J s-' m-², from a body at temperature Tis 1 = GT*, where e is Stefan-Boltzmann's constant. Because black-body radiation can be considered to be a gas of photons, i.e. quantum particles which move with velocity e with typical energies of the order of kT, the intensity I is a function of h, c and kT. Use dimensional analysis to confirm that Iis proportional to 7 and find the dependence of a on h and c.arrow_forward
- Physics for Scientists and Engineers with Modern ...PhysicsISBN:9781337553292Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningCollege PhysicsPhysicsISBN:9781305952300Author:Raymond A. Serway, Chris VuillePublisher:Cengage LearningPhysics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage Learning
- Physics for Scientists and EngineersPhysicsISBN:9781337553278Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningCollege PhysicsPhysicsISBN:9781285737027Author:Raymond A. Serway, Chris VuillePublisher:Cengage LearningPrinciples of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning