Question: A 75-W light source consumes 75

> A large number of neon atoms are in thermal equilibrium. What is the ratio of the number of atoms in a 5s state to the number in a 3p state at a. 300 K; b. 600 K; c. 1200 K? The energies of these states, relative to the ground state, are E5s = 20.66 e

> Photorefractive keratectomy (PRK) is a laser-based surgical procedure that corrects near- and farsightedness by removing part of the lens of the eye to change its curvature and hence focal length. This procedure can remove layers 0.25 µm thick using puls

> How many photons per second are emitted by a 7.50-mW CO2 laser that has a wavelength of 10.6 µm?

> Pulsed dye lasers emit light of wavelength 585 nm in 0.45-ms pulses to remove skin blemishes such as birthmarks. The beam is usually focused onto a circular spot 5.0 mm in diameter. Suppose that the output of one such laser is 20.0 W. a. What is the ene

> Using a mixture of CO2, N2, and sometimes He, CO2 lasers emit a wavelength of 10.6 mm. At power outputs of 0.100 kW, such lasers are used for surgery. How many photons per second does a CO2 laser deliver to the tissue during its use in an operation?

> Use Balmer’s formula to calculate a. the wavelength, b. the frequency, and c. the photon energy for the Hg line of the Balmer series for hydrogen.

> a. An atom initially in an energy level with E = -6.52 eV absorbs a photon that has wavelength 860 nm. What is the internal energy of the atom after it absorbs the photon? b. An atom initially in an energy level with E = -2.68 eV emits a photon that has

> In a set of experiments on a hypothetical one electron atom, you measure the wavelengths of the photons emitted from transitions ending in the ground level (n = 1), as shown in the energy-level diagram in Fig. E39.27. You also observe that it takes 17.50

> a. For one-electron ions with nuclear charge Z, what is the speed of the electron in a Bohr-model orbit labeled with n? Give your answer in terms of v1, the orbital speed for the n = 1 Bohr orbit in hydrogen. b. What is the largest value of Z for which

> The energy-level scheme for the hypothetical one electron element Searsium is shown in Fig. E39.25. The potential energy is taken to be zero for an electron at an infinite distance from the nucleus. a. How much energy (in electron volts) does it take to

> Can an image formed by one reflecting or refracting surface serve as an object for a second reflection or refraction? Does it matter whether the first image is real or virtual? Explain.

> Consider the Bohr-model description of a hydrogen atom. a. Calculate K1, U1, and E1 for the n = 1 energy level. How are K1 and U1 related? b. Show that for any value of n, both Un = -2Kn and Kn = -En

> Consider the Bohr-model description of a hydrogen atom. a. Calculate E2 - E1 and E10 - E9 . As n increases, does the energy separation between adjacent energy levels increase, decrease, or stay the same? b. Show that En+1 - En approaches (27.2 eV)/n3 a

> A triply ionized beryllium ion, Be3+ (a beryllium atom with three electrons removed), behaves very much like a hydrogen atom except that the nuclear charge is four times as great. a. What is the ground-level energy of Be3+? How does this compare to the

> A beam of alpha particles is incident on a target of lead. A particular alpha particle comes in “head-on” to a particular lead nucleus and stops 6.50 * 10-14 m away from the center of the nucleus. (This point is well outside the nucleus.) Assume that the

> A 4.78-MeV alpha particle from a 226-Ra decay makes a head-on collision with a uranium nucleus. A uranium nucleus has 92 protons. a. What is the distance of closest approach of the alpha particle to the center of the nucleus? Assume that the uranium nuc

> A beam of electrons is accelerated from rest through a potential difference of 0.100 kV and then passes through a thin slit. When viewed far from the slit, the diffracted beam shows its first diffraction minima at ±14.6° from the original direction of th

> A doubly ionized lithium atom (Li++) is one that has had two of its three electrons removed. The energy levels of the remaining single-electron ion are closely related to those of the hydrogen atom. The nuclear charge for lithium is +3e instead of just +

> When an electron beam goes through a very small hole, it produces a diffraction pattern on a screen, just like that of light. Does this mean that an electron spreads out as it goes through the hole? What does this pattern mean?

> When you check the air pressure in a tire, a little air always escapes; the process of making the measurement changes the quantity being measured. Think of other examples of measurements that change or disturb the quantity being measured.

> Why can an electron microscope have greater magnification than an ordinary microscope?

> A spherical air bubble in water can function as a lens. Is it a converging or diverging lens? How is its focal length related to its radius?

> As the lower half of Fig. 39.4 shows, the diffraction pattern made by electrons that pass through aluminum foil is a series of concentric rings. But if the aluminum foil is replaced by a single crystal of aluminum, only certain points on these rings appe

> Could an electron-diffraction experiment be carried out using three or four slits? Using a grating with many slits? What sort of results would you expect with a grating? Would the uncertainty principle be violated? Explain.

> Laser light results from transitions from long-lived metastable states. Why is it more monochromatic than ordinary light?

> Suppose a two-slit interference experiment is carried out using an electron beam. Would the same interference pattern result if one slit at a time is uncovered instead of both at once? If not, why not? Doesn’t each electron go through one slit or the oth

> Which has more total energy: a hydrogen atom with an electron in a high shell (large n) or in a low shell (small n)? Which is moving faster: the high-shell electron or the low-shell electron? Is there a contradiction here? Explain.

> As a body is heated to a very high temperature and becomes self-luminous, the apparent color of the emitted radiation shifts from red to yellow and finally to blue as the temperature increases. Why does the color shift? What other changes in the characte

> The emission of a photon by an isolated atom is a recoil process in which momentum is conserved. Thus Eq. (39.5) should include a recoil kinetic energy Kr for the atom. Why is this energy negligible in that equation?

> a. If the average frequency emitted by a 120-W light bulb is 5.00 * 1014 Hz and 10.0% of the input power is emitted as visible light, approximately how many visible-light photons are emitted per second? b. At what distance would this correspond to 1.00

> To test the photon concept, you perform a Compton-scattering experiment in a research lab. Using photons of very short wavelength, you measure the wavelength λ′ of scattered photons as a function of the scattering angle &Ea

> While analyzing smoke detector designs that rely on the photoelectric effect, you are evaluating surfaces made from each of the materials listed in Table 38.1. One particular application uses ultraviolet light with wavelength 270 nm. a. For which of the

> When a converging lens is immersed in water, does its focal length increase or decrease in comparison with the value in air? Explain.

> In developing night-vision equipment, you need to measure the work function for a metal surface, so you perform a photoelectric-effect experiment. You measure the stopping potential V0 as a function of the wavelength λ of the light that is i

> An x-ray photon is scattered from a free electron (mass m) at rest. The wavelength of the scattered photon is λ′, and the final speed of the struck electron is v. a. What was the initial wavelength λ of the photon? Express your answer in terms of λ′, v,

> A photon with wavelength 0.1100 nm collides with a free electron that is initially at rest. After the collision the wavelength is 0.1132 nm. a. What is the kinetic energy of the electron after the collision? What is its speed? b. If the electron is sud

> An x-ray tube is operating at voltage V and current I. a. If only a fraction p of the electric power supplied is converted into x rays, at what rate is energy being delivered to the target? b. If the target has mass m and specific heat c (in J/kg.K), a

> Nuclear fusion reactions at the center of the sun produce gamma-ray photons with energies of about 1 MeV (106 eV). By contrast, what we see emanating from the sun’s surface are visible light photons with wavelengths of about 500 nm. A simple model that e

> A photon of wavelength 4.50 pm scatters from a free electron that is initially at rest. a. For ɸ = 90.0°, what is the kinetic energy of the electron immediately after the collision with the photon? What is the ratio of this kinetic energy to the rest en

> A photon with wavelength λ = 0.1050 nm is incident on an electron that is initially at rest. If the photon scatters at an angle of 60.0° from its original direction, what are the magnitude and direction of the linear momentum of the electron just after i

> A photon with wavelength λ = 0.0980 nm is incident on an electron that is initially at rest. If the photon scatters in the backward direction, what is the magnitude of the linear momentum of the electron just after the collision with the photon?

> An incident x-ray photon of wavelength 0.0900 nm is scattered in the backward direction from a free electron that is initially at rest. a. What is the magnitude of the momentum of the scattered photon? b. What is the kinetic energy of the electron afte

> A 2.50-W beam of light of wavelength 124 nm falls on a metal surface. You observe that the maximum kinetic energy of the ejected electrons is 4.16 eV. Assume that each photon in the beam ejects a photoelectron. a. What is the work function (in electron

> A tank whose bottom is a mirror is filled with water to a depth of 20.0 cm. A small fish floats motionless 7.0 cm under the surface of the water. a. What is the apparent depth of the fish when viewed at normal incidence? b. What is the apparent depth o

> How much energy is imparted to one cell during one day’s treatment? Assume that the specific gravity of the tumor is 1 and that 1 J = 6 * 1018 eV. a. 120 keV; b. 12 MeV; c. 120 MeV; d. 120 * 103 MeV.

> Higher-energy photons might be desirable for the treatment of certain tumors. Which of these actions would generate higher-energy photons in this linear accelerator? a. Increasing the number of electrons that hit the tungsten target; b. accelerating th

> The probability of a photon interacting with tissue via the photoelectric effect or the Compton effect depends on the photon energy. Use Fig. P38.44 to determine the best description of how the photons from the linear accelerator described in the passage

> The high-energy photons can undergo Compton scattering off electrons in the tumor. The energy imparted by a photon is a maximum when the photon scatters straight back from the electron. In this process, what is the maximum energy that a photon with the e

> A laser used to weld detached retinas emits light with a wavelength of 652 nm in pulses that are 20.0 ms in duration. The average power during each pulse is 0.600 W. a. How much energy is in each pulse in joules? In electron volts? b. What is the energ

> An electron and a positron are moving toward each other and each has speed 0.500c in the lab frame. a. What is the kinetic energy of each particle? b. The e+ and e- meet head-on and annihilate. What is the energy of each photon that is produced? c. Wh

> X rays with initial wavelength 0.0665 nm undergo Compton scattering. What is the longest wavelength found in the scattered x rays? At which scattering angle is this wavelength observed?

> When ultraviolet light with a wavelength of 254 nm falls on a clean copper surface, the stopping potential necessary to stop emission of photoelectrons is 0.181 V. a. What is the photoelectric threshold wavelength for this copper surface? b. What is th

> The photoelectric threshold wavelength of a tungsten surface is 272 nm. Calculate the maximum kinetic energy of the electrons ejected from this tungsten surface by ultraviolet radiation of frequency 1.45 * 1015 Hz. Express the answer in electron volts.

> How could you very quickly make an approximate measurement of the focal length of a converging lens? Could the same method be applied if you wished to use a diverging lens? Explain.

> A photon has momentum of magnitude 8.24 * 10-28 kg.m/s. a. What is the energy of this photon? Give your answer in joules and in electron volts. b. What is the wavelength of this photon? In what region of the electromagnetic spectrum does it lie?

> Most black-and-white photographic film (with the exception of some special-purpose films) is less sensitive to red light than blue light and has almost no sensitivity to infrared. How can these properties be understood on the basis of photons?

> During the photoelectric effect, light knocks electrons out of metals. So why don’t the metals in your home lose their electrons when you turn on the lights?

> In what ways do photons resemble other particles such as electrons? In what ways do they differ? Do photons have mass? Do they have electric charge? Can they be accelerated? What mechanical properties do they have?

> In attempting to reconcile the wave and particle models of light, some people have suggested that the photon rides up and down on the crests and troughs of the electromagnetic wave. What things are wrong with this description?

> A photon of frequency f undergoes Compton scattering from an electron at rest and scatters through an angle ɸ. The frequency of the scattered photon is f ′. How is f ′ related to f? Does your answer depend on ɸ? Explain.

> The materials called phosphors that coat the inside of a fluorescent lamp convert ultraviolet radiation (from the mercury vapor discharge inside the tube) into visible light. Could one also make a phosphor that converts visible light to ultraviolet? Expl

> In an experiment involving the photoelectric effect, if the intensity of the incident light (having frequency higher than the threshold frequency) is reduced by a factor of 10 without changing anything else, which (if any) of the following statements abo

> Explain why Fig. 38.4 shows that most photoelectrons have kinetic energies less than hf - ɸ, and also explain how these smaller kinetic energies occur.

> Consider Compton scattering of a photon by a moving electron. Before the collision the photon has wavelength λ and is moving in the +x-direction, and the electron is moving in the –x-direction with total energy E (including

> A spherical, concave shaving mirror has a radius of curvature of 32.0 cm. a. What is the magnification of a person’s face when it is 12.0 cm to the left of the vertex of the mirror? b. Where is the image? Is the image real or virtual? c. Draw a princip

> The starships of the Solar Federation are marked with the symbol of the federation, a circle, while starships of the Denebian Empire are marked with the empire’s symbol, an ellipse whose major axis is 1.40 times longer than its minor ax

> After being produced in a collision between elementary particles, a positive pion (π+) must travel down a 1.90-km-long tube to reach an experimental area. A π+ particle has an average lifetime (measured in its rest frame) of 2.60 * 10-8 s; the π+ we are

> You are a scientist studying small aerosol particles that are contained in a vacuum chamber. The particles carry a net charge, and you use a uniform electric field to exert a constant force of 8.00 * 10-14 N on one of them. That particle moves in the dir

> You are an astronomer investigating four astronomical sources of infrared radiation. You have identified the nature of each source, so you know the frequency f0 of each when it is at rest relative to you. Your detector, which is at rest relative to the e

> As a research scientist at a linear accelerator, you are studying an unstable particle. You measure its mean lifetime ∆t as a function of the particle’s speed relative to your laboratory equipment. You record the speed

> The French physicist Armand Fizeau was the first to measure the speed of light accurately. He also found experimentally that the speed, relative to the lab frame, of light traveling in a tank of water that is itself moving at a speed V relative to the la

> A spaceship moving at constant speed u relative to us broadcasts a radio signal at constant frequency f0. As the spaceship approaches us, we receive a higher frequency f; after it has passed, we receive a lower frequency. a. As the spaceship passes by,

> A baseball coach uses a radar device to measure the speed of an approaching pitched baseball. This device sends out electromagnetic waves with frequency f0 and then measures the shift in frequency ∆f of the waves reflected from the moving baseball. If th

> Einstein and Lorentz, being avid tennis players, play a fast-paced game on a court where they stand 20.0 m from each other. Being very skilled players, they play without a net. The tennis ball has mass 0.0580 kg. You can ignore gravity and assume that th

> Two events are observed in a frame of reference S to occur at the same space point, the second occurring 1.80 s after the first. In a frame S′ moving relative to S, the second event is observed to occur 2.15 s after the first. What is the difference betw

> Suppose that in the situation of Example 34.7 of Section 34.3 (see Fig. 34.26) a vertical arrow 2.00 m tall is painted on the side of the pool beneath the water line. According to the calculations in the example, this arrow would appear to the person sho

> In the earth’s rest frame, two protons are moving away from each other at equal speed. In the frame of each proton, the other proton has a speed of 0.700c. What does an observer in the rest frame of the earth measure for the speed of each proton?

> The distance to a particular star, as measured in the earth’s frame of reference, is 7.11 light-years (1 light-year is the distance that light travels in 1 y). A spaceship leaves the earth and takes 3.35 y to arrive at the star, as measured by passengers

> Two atomic clocks are carefully synchronized. One remains in New York, and the other is loaded on an airliner that travels at an average speed of 250 m/s and then returns to New York. When the plane returns, the elapsed time on the clock that stayed behi

> The net force F on a particle of mass m is directed at 30.0° counterclockwise from the +x-axis. At one instant of time, the particle is traveling in the +x-direction with a speed (measured relative to the earth) of 0.700c. At this instant, what is the di

> A muon is created 55.0 km above the surface of the earth (as measured in the earth’s frame). The average lifetime of a muon, measured in its own rest frame, is 2.20 µs, and the muon we are considering has this lifetime. In the frame of the muon, the eart

> A space probe is sent to the vicinity of the star Capella, which is 42.2 light-years from the earth. (A light-year is the distance light travels in a year.) The probe travels with a speed of 0.9930c. An astronaut recruit on board is 19 years old when the

> A cube of metal with sides of length a sits at rest in a frame S with one edge parallel to the x-axis. Therefore, in S the cube has volume a3. Frame S′ moves along the x-axis with a speed u. As measured by an observer in frame S′, what is the volume of t

> In the alternate universe, how fast must an object be moving for it to have a kinetic energy equal to its rest mass? a. 225 m/s; b. 260 m/s; c. 300 m/s; d. The kinetic energy could not be equal to the rest mass.

> If the airplane of Passage Problem 37.71 has a rest mass of 20,000 kg, what is its relativistic mass when the plane is moving at 180 m/s ? a. 8000 kg; b. 12,000 kg; c. 16,000 kg; d. 25,000 kg; e. 33,300 kg. From Passage Problem 37.71 An airplane h

> An airplane has a length of 60 m when measured at rest. When the airplane is moving at 180 m/s (400 mph) in the alternate universe, how long would the plane appear to be to a stationary observer? a. 24 m; b. 36 m; c. 48 m; d. 60 m; e. 75 m.

> In Example 34.4 (Section 34.2), there appears to be an ambiguity for the case s = 10 cm as to whether s ′ is +∞ or -∞ and whether the image is erect or inverted. How is this resolved? Or is it? From

> A spaceship flies past Mars with a speed of 0.985c relative to the surface of the planet. When the spaceship is directly overhead, a signal light on the Martian surface blinks on and then off. An observer on Mars measures that the signal light was on for

> The positive muon (µ+), an unstable particle, lives on average 2.20 * 10-6 s (measured in its own frame of reference) before decaying. a. If such a particle is moving, with respect to the laboratory, with a speed of 0.900c, what average lifetime is meas

> Suppose the two lightning bolts shown in Fig. 37.5a are simultaneous to an observer on the train. Show that they are not simultaneous to an observer on the ground. Which lightning strike does the ground observer measure to come first? Lightning hits

> The sun produces energy by nuclear fusion reactions, in which matter is converted into energy. By measuring the amount of energy we receive from the sun, we know that it is producing energy at a rate of 3.8 * 1026 W. a. How many kilograms of matter does

> What is the kinetic energy of a proton moving at a. 0.100c; b. 0.500c; c. 0.900c? How much work must be done to d. increase the proton’s speed from 0.100c to 0.500c and e. increase the proton’s speed from 0.500c to 0.900c? f. How do the last two re

> Two protons (each with rest mass M = 1.67 * 10-27 kg) are initially moving with equal speeds in opposite directions. The protons continue to exist after a collision that also produces an h0 particle (see Chapter 44). The rest mass of the h0 is m = 9.75 *

> A particle has rest mass 6.64 * 10-27 kg and momentum 2.10 * 10-18 kg.m/s. a. What is the total energy (kinetic plus rest energy) of the particle? b. What is the kinetic energy of the particle? c. What is the ratio of the kinetic energy to the rest en

> Electrons are accelerated through a potential difference of 750 kV, so that their kinetic energy is 7.50 * 105 eV. a. What is the ratio of the speed v of an electron having this energy to the speed of light, c? b. What would the speed be if it were com

> To determine whether a frog can judge distance by means of the amount its lens must move to focus on an object, researchers covered one eye with an opaque material. An insect was placed in front of the frog, and the distance that the frog snapped its ton

> Given that frogs are nearsighted in air, which statement is most likely to be true about their vision in water? a. They are even more nearsighted; because water has a higher index of refraction than air, a frog’s ability to focus light increases in wate

> A person looks at his reflection in the concave side of a shiny spoon. Is it right side up or inverted? Does it matter how far his face is from the spoon? What if he looks in the convex side? (Try this yourself!)

> What is the farthest distance at which a typical “nearsighted” frog can see clearly in air? a. 12 m; b. 6.0 m; c. 80 cm; d. 17 cm.

> A frog can see an insect clearly at a distance of 10 cm. At that point the effective distance from the lens to the retina is 8 mm. If the insect moves 5 cm farther from the frog, by how much and in which direction does the lens of the frog’s eye have to