Yolanda, whose mass is 64.2 kg, is riding in an elevator that has an upward acceleration of 2.13 m/s2. What force does she exert on the floor of the elevator?
> A certain nuclide absorbs a neutron. It then emits an electron, and then breaks up into two alpha particles. (a) Identify the original nuclide and the two intermediate nuclides (after absorbing the neutron and after emitting the electron). (b) Would an
> A scuba diver in a lake aims her underwater spotlight at the lake surface. (a) If the beam makes a 75° angle of incidence with respect to a normal to the water surface, is it reflected, transmitted, or both? Find the angles of the reflected and transmitt
> A neutron-activated sample emits gamma rays at energies that are consistent with the decay of mercury-198 nuclei from an excited state to the ground state. If the reaction that takes place is , what is the nuclide “(?)”
> A laser beam is traveling through an unknown substance. When it encounters a boundary with air, the angle of reflection is 25.0° and the angle of refraction is 37.0°. (a) What is the index of refraction of the substance? (b) What is the speed of light
> Make an order-of-magnitude estimate of the amount of radon- 222 gas, measured in curies, found in the lungs of an average person. Assume an average exposure of 1 mSv/yr due to the alpha particles emitted by radon-222. The half-life is 3.8 days. You will
> While on an elevator, Jaden's apparent weight is 550 N. When he was on the ground, the scale reading was 600 N. What is Jaden's acceleration?
> In many cars the passenger's side mirror says: “Objects in the mirror are closer than they appear.” (a) Does this mirror form real or virtual images? (b) Since the image is diminished in size, is the mirror concave or convex? Why? (c) Show that the im
> The greatest concentration of iodine in the body is in the thyroid gland, so radioactive iodine-131 is often used as a tracer to help diagnose thyroid problems. Suppose the activity of 131I in a patient’s thyroid is initially 1.85 × 106 Bq. 131I decays v
> Samantha puts her face 32.0 cm from a makeup mirror and notices that her image is magnified by 1.80 times. (a) What kind of mirror is this? (b) Where is her face relative to the radius of curvature or focal length? (c) What is the radius of curvature
> Some types of cancer can be effectively treated by bombarding the cancer cells with high energy protons. Suppose 1.16 × 1017 protons, each with an energy of 950 keV, are incident on a tumor of mass 3.82 mg. If the RBE for these protons is 3.0, what is th
> A 5.0 cm tall object is placed 50.0 cm from a lens with focal length −20.0 cm. (a) How tall is the image? (b) Is the image upright or inverted?
> If meat is irradiated with 2000.0 Gy of x-rays, most of the bacteria are killed and the shelf life of the meat is greatly increased. (a) How many 100.0 keV photons must be absorbed by a 0.30 kg steak so that the absorbed dose is 2000.0 Gy? (b) Assuming
> A concave mirror has a radius of curvature of 14 cm. If a pointlike object is placed 9.0 cm away from the mirror on its principal axis, where is the image?
> A 65 kg patient undergoes a diagnostic chest x-ray and receives a biologically equivalent dose of 0.2 mSv distributed over 33% of the patient’s body mass. If the x-rays have a relative biological effectiveness of 0.90, how much energy is absorbed by the
> An object is placed 10.0 cm in front of a lens. An upright, virtual image is formed 30.0 cm away from the lens. What is the focal length of the lens? Is the lens converging or diverging?
> An alpha particle produced in radioactive decay has a kinetic energy of typically about 6 MeV. When an alpha particle passes through matter (e.g., biological tissue), it makes ionizing collisions with molecules, giving up some of its kinetic energy to su
> A 115 g ball is traveling to the left with a speed of 30 m/s when it is struck by a racket. The force on the ball, directed to the right and applied over 21 ms of contact time, is shown in the graph. What is the speed of the ball immediately after it lea
> An object 8.0 cm high forms a virtual image 3.5 cm high located 4.0 cm behind a mirror. (a) Find the object distance. (b) Describe the mirror: is it plane, convex, or concave? (c) What are its focal length and radius of curvature?
> A sample of potassium-40 has an activity of 9.0 mCi. What is its mass?
> A point source of light is placed 10 cm in front of a concave mirror; the reflected rays are parallel. What is the radius of curvature of the mirror?
> A radioactive sample has equal numbers of 15O and 19O nuclei. Use the half-lives found in Appendix B.8 to determine how long it will take before there are twice as many 15O nuclei as 19O. What percent of the 19O nuclei have decayed during this time?
> You are standing 1.2 m from a heat lamp that draws an rms current of 12.5 A when connected to 120 V rms. (a) Assuming that the energy of the heat lamp is radiated uniformly in a hemispherical pattern, what is the intensity of the light on your face? (b
> To perform a bone scan, 3.8 × 106 Bq of 85Sr is injected into a patient. The half-life of 85Sr is 30.1 yr, and its mass is 84.9 u. What mass of 85Sr is injected into the patient?
> Using Faraday’s law, show that if a magnetic dipole antenna’s axis makes an angle θ with the magnetic field of an EM wave, the induced emf in the antenna is reduced from its maximum possible value by a factor of cos θ. [Hint: Assume that, at any instant,
> In this problem, you will verify the statement (in Section 29.4) that the 14C activity in a living sample is 0.25 Bq per gram of carbon. (a) What is the decay constant λ for 14C? (b) How many 14C atoms are in 1.00 g of carbon? One mole of carbon atoms h
> Verify that the equation I = 〈u〉c is dimensionally consistent (i.e., check the units).
> A certain radioactive nuclide has a half-life of 200.0 s. A sample containing just this one radioactive nuclide has an initial activity of 80 000.0 s−1. (a) What is the activity 600.0 s later? (b) How many nuclei were there initially? (c) What is the
> When on the ground, Ian's weight is measured to be 640 N. When Ian is on an elevator, his apparent weight is 700 N. What is the net force on the system (Ian and the elevator) if their combined mass is 1050 kg?
> A microwave oven can heat 350 g of water from 25.0°C to 100.0°C in 2.00 min. (a) At what rate is energy absorbed by the water? (b) These microwaves pass through a waveguide of cross-sectional area 88.0 cm2. What is the average intensity of the microwav
> Refer to Example 28.6. Estimate the percentage change in the tunneling current if the distance between the sample surface and the STM tip increases 2.0%.
> By expressing ϵ0 and μ0 in base SI units (kg, m, s, A), show that the only combination of the two with dimensions of speed is (ϵ0μ0)−1/2.
> A proton and a deuteron (which has the same charge as the proton but 2.0 times the mass) are incident on a barrier of thickness 10.0 fm and “height” 10.0 MeV. Each particle has a kinetic energy of 3.0 MeV. (a) Which particle has the higher probability o
> What are the three lowest angular speeds for which the wheel in Fizeau’s apparatus (see Fig. 22.11) allows the reflected light to pass through to the observer? Assume the distance between the notched wheel and the mirror is 8.6 km and that there are 5 no
> In a ruby laser, laser light of wavelength 694.3 nm is emitted. The ruby crystal is 6.00 cm long, and the index of refraction of ruby is 1.75. Think of the light in the ruby crystal as a standing wave along the length of the crystal. How many wavelengths
> To measure the speed of light, Galileo and a colleague stood on different mountains with covered lanterns. Galileo uncovered his lantern and his friend, seeing the light, uncovered his own lantern in turn. Galileo measured the elapsed time from uncoverin
> A photoconductor (see Conceptual Question 13) allows charge to flow freely when photons of wavelength 640 nm or less are incident on it. What is the band gap for this photoconductor?
> You are trying to communicate with a spaceship that is traveling at 1.2 × 108 m/s away from Earth. If you send a message at a frequency of 55 kHz, to what frequency should the astronauts on the ship tune to receive your message?
> A light-emitting diode (LED) has the property that electrons can be excited into the conduction band by the electrical energy from a battery; a photon is emitted when the electron drops back to the valence band. (a) If the band gap for this diode is 2.3
> You take a homemade “accelerometer” to an amusement park. This accelerometer consists of a metal nut attached to a string and connected to a protractor, as shown in the figure. While riding a roller coaster that is mov
> A 10 W laser emits a beam of light 4.0 mm in diameter. The laser is aimed at the Moon. By the time it reaches the Moon, the beam has spread out to a diameter of 85 km. Ignoring absorption by the atmosphere, what is the intensity of the light (a) just ou
> (a) Find the magnitude of the orbital angular momentum L for an electron with n = 2 and I = 1 in terms of ħ. (b) What are the allowed values for Lz? (c) What are the angles between the positive z-axis and / so that the quantized components, Lz, have a
> Energy carried by an EM wave coming through the air can be used to light a bulb that is not connected to a battery or plugged into an electric outlet. Suppose a receiving antenna is attached to a bulb and the bulb is found to dissipate a maximum power of
> An electron in a hydrogen atom has quantum numbers: n = 8; mℓ = 4. What are the possible values for the orbital angular momentum quantum number ℓ of the electron?
> A sinusoidal EM wave has an electric field amplitude Em = 32.0 mV/m. What are the intensity and average energy density? [Hint: Recall the relationship between amplitude and rms value for a quantity that varies sinusoidally.]
> What is the electronic configuration of the ground state of the carbon atom? Write it in the following ways: (a) using spectroscopic notation (1s2 …); (b) listing the four quantum numbers for each of the electrons. Note that there may be more than one
> An unpolarized beam of light (intensity I0) is moving in the x- direction. The light passes through three ideal polarizers whose transmission axes are (in order) at angles 0.0°, 45.0°, and 30.0° counterclockwise from the y-axis in the yz-plane. (a) What
> A muon and an antimuon, each with a mass that is 207 times greater than an electron, were at rest when they annihilated and produced two photons of equal energy. What is the wavelength of each of the photons?
> Polarized light of intensity I0 is incident on a pair of ideal polarizing sheets. Let θ1 and θ2 be the angles between the direction of polarization of the incident light and the transmission axes of the first and second sheets, respectively. Show that th
> A photon passes near a nucleus and creates an electron and a positron, each with a total energy of 8.0 MeV. What was the wavelength of the photon?
> The range of wavelengths allotted to the radio broadcast band is from about 190 m to 550 m. If each station needs exclusive use of a frequency band 10 kHz wide, how many stations can operate in the broadcast band?
> A positron emission tomography (PET) scanner detects 511 keV photons emitted when positrons and electrons annihilate each other. What is the wavelength of the photons?
> A 2.0 mW laser pointer has a beam diameter of 1.5 mm. When it is accidentally pointed at a person’s eye, the beam is focused to a spot of diameter 20.0 µm on the retina and the retina is exposed for 80 ms. (a) What is the intensity of the laser beam? (b
> A photon with a wavelength in the visible region (between 400 and 700 nm) causes a transition from the n to the (n + 1) state in doubly ionized lithium (Li2+). What is the lowest value of n for which this could occur?
> (a) What is the total energy of a single pulse? (b) What is the intensity during a pulse?
> (a) Find the energies of the first four levels of doubly ionized lithium (Li2+), starting with n = 1. (b) What are the energies of the photons emitted or absorbed when the electron makes a transition between these levels? (c) Are any of the photons in t
> a) In what part of the EM spectrum is the laser pulse? (b) How long (in centimeters) is a single pulse of the laser in air? (c) How many wavelengths fit in one pulse?
> Find the energy in electron-volts required to remove the remaining electron from a doubly ionized lithium (Li2+) atom.
> Two identical television signals are sent between two cities that are 400.0 km apart. One signal is sent through the air, and the other signal is sent through a fiber optic network. The signals are sent at the same time, but the one traveling through air
> Find the Bohr radius of doubly ionized lithium (Li2+).
> What’s the quickest way to make a U-turn at constant speed? Suppose that you need to make a 180° turn on a circular path. The minimum radius (due to the car’s steering system) is 5.0 m, while the maximum (due to the width of the road) is 20.0 m. Your acc
> The antenna on a wireless router radiates microwaves at a frequency of 5.0 GHz. What is the maximum length of the antenna if it is not to exceed half of a wavelength?
> (a) What is the difference in radius between the n = 1 state and the n = 2 state for hydrogen? (b) What is the difference in radius between the n = 100 state and the n = 101 state for hydrogen? How do the neighboring orbital separations compare for larg
> Astronauts on the Moon communicated with mission control in Houston via EM waves. There was a noticeable time delay in the conversation due to the round-trip transit time for the EM waves between the Moon and Earth. How long was the time delay?
> What is the orbital radius of the electron in the n = 3 state of hydrogen?
> A hydroelectric power plant is situated at the base of a dam. Water exits the power plant 120 m below the top of the reservoir at a speed of about 4 m/s (at atmospheric pressure). The volume flow rate of water through the power plant is 1000 m3/s. The pl
> By directly substituting the values of the fundamental constants, show that the ground state energy for hydrogen in the Bohr model E1 = −mek2e4/(2ℏ2) has the numerical value −13.6 eV.
> Consider an induction stove utilizing a primary heating coil located just beneath the stove top. The circuit elements in the stove supply the coil with a peak ac voltage of 340 V at a frequency of 50 kHz. The coil has 18 turns; its inductance is 80 µH an
> By directly substituting the values of the fundamental constants, show that the Bohr radius a0 = ℏ2/(meke2) has the numerical value 5.29 × 10−11 m.
> Suppose a power plant produces 800 kW of power and is to send that power for many miles over a copper wire with a total resistance of 12 Ω. (a) If the power is sent across the copper wires at 48 kV rms, how much current flows through the wires? (b) Wha
> A fluorescent solid absorbs a photon of ultraviolet light of wavelength 320 nm. If the solid dissipates 0.500 eV of the energy and emits the rest in a single photon, what is the wavelength of the emitted light?
> Oliver has a mass of 76.2 kg. He is riding in an elevator that has a downward acceleration of 1.37 m/s2. With what magnitude force does the elevator floor push upward on Oliver?
> A parallel plate capacitor has two plates, each of area 3.0 × 10−4 m2, separated by 3.5 × 10−4 m. The space between the plates is filled with a dielectric. When the capacitor is connected to a source of 120 V rms at 8.0 kHz, an rms current of 1.5 × 10−4
> The Paschen series in the hydrogen emission spectrum is formed by electron transitions from ni > 3 to nf = 3. (a) What is the longest wavelength in the Paschen series? (b) What is the wavelength of the series limit (the lower bound of the wavelengths i
> An RLC series circuit is connected to a 240 V rms power supply at a frequency of 2.50 kHz. The elements in the circuit have the following values: R = 12.0 Ω, C = 0.26 µF, and L = 15.2 mH. (a) What is the impedance of the circuit? (b) What is the rms cu
> If an atom had only four distinct energy levels between which electrons could make transitions, how many spectral lines of different wavelengths could the atom emit?
> (a) What is the reactance of a 5.00 µF capacitor at the frequencies f = 12.0 Hz and 1.50 kHz? (b) What is the impedance of a series combination of the 5.00 µF capacitor and a 2.00 kΩ resistor at the same two frequencies? (c) What is the maximum current
> A hydrogen atom has an electron in the n = 5 level. (a) If the electron returns to the ground state by emitting radiation, what is the minimum number of photons that can be emitted? (b)What is the maximum number that might be emitted?
> In an RLC circuit, these three elements are connected in series: a resistor of 20.0 Ω, a 35.0 mH inductor, and a 50.0 µF capacitor. The ac source of the circuit has an rms voltage of 100.0 V and an angular frequency of 1.0 × 103 rad/s. (a) Find the rms
> The hydrogen atom emits a photon when making a transition between energy levels ni → nf. Rank the transitions according to the wavelength of the emitted photon, largest to smallest. (a) 4 → 2; (b) 3 → 1; (c) 2 → 1; (d) 3 → 2; (e) 4 → 3; (f) 5 → 4.
> A 40.0 mH inductor, with internal resistance of 30.0 Ω, is connected to an ac source (a) What is the impedance of the inductor in the circuit? (b) What are the peak and rms voltages across the inductor (including the internal resistance)? (
> Starting with the energy-momentum relation and the definition of total energy, show that (pc)2 = K2 + 2KE0 [Eq. (26-23)].
> A student, looking toward his fourth-floor dormitory window, sees a flowerpot with nasturtiums (originally on a window sill above) pass his 1.0 m high window in 0.051 s. The distance between floors in the dormitory is 4.0 m. From a window on which floor
> A certain circuit has a 25 Ω resistor and one other component in series with a 12 V (rms) sinusoidal ac source. The rms current in the circuit is 0.317 A when the frequency is 150 Hz and increases by 25.0% when the frequency increases to 250 Hz. (a) Wha
> Derive the energy-momentum relation Start by squaring the definition of total energy (E = K + E0) and then use the relativistic expressions for momentum and kinetic energy [Eqs. (26-15) and (26-18)].
> Transformers are often rated in terms of kilovoltamps. A pole on a residential street has a transformer rated at 35 kVA to serve four homes on the street. (a) If each home has a fuse that limits the incoming current to 60 A rms at 220 V rms, find the ma
> In a beam of electrons used in a diffraction experiment, each electron is accelerated to a kinetic energy of 150 keV. (a) Are the electrons relativistic? Explain. (b) How fast are the electrons moving?
> (a) Calculate the rms current drawn by the load in the figure with Problem 88 if / kV and the average power supplied by the generator is 12 MW. (b) Suppose that the average power supplied by the generator is still 12 MW, but the load is not purely resi
> For a nonrelativistic particle of mass m, show that K = p2/(2m). [Hint: Start with the nonrelativistic expressions for kinetic energy K and momentum p.]
> A generator supplies an average power of 12 MW through a transmission line that has a resistance of 10.0 Ω. What is the power loss in the transmission line if the rms line voltage / is (a) 15 kV and (b) 110 kV? What percentage of the tota
> An experimental form of cancer therapy involves the use of a beam of highly ionized carbon atoms with a charge of +6e (all six electrons have been removed). The mass of the ions is 11.172 GeV/c2. If the accelerator is 7.50 m long and the ions are acceler
> A variable inductor is connected to a voltage source whose frequency can vary. The rms current is Ii. If the inductance is increased by a factor of 3.0 and the frequency is reduced by a factor of 2.0, what will be the new rms current in the circuit? The
> In a medical treatment known as fast-neutron therapy, neutrons of kinetic energy 25 MeV are directed toward a patient's tumor. Neutrons are known to decay, when at rest, with an average lifetime of 886 s. What is the lifetime, as measured in the laborato
> A person stands on a bathroom scale in an elevator. Rank the scale readings from highest to lowest based on the given information about the speed v or the magnitude of the acceleration a. (a) ascending with increasing speed (a = 1.0 m/s2); (b) descendi
> An antibaryon with charge +e composed of up and/or strange quarks and/or antiquarks.
> An RLC circuit has a resistance of 255 Ω, an inductance of 146 mH, and a capacitance of 877 nF. (a) What is the resonant frequency of this circuit? (b) If this circuit is connected to a sinusoidal generator with a frequency 0.50 times the resonant frequ
> PET scans involve the use of positron-emitting isotopes like carbon-11 and fluorine-18. These isotopes can be produced at hospital-based accelerators that first accelerate deuterons (hydrogen-2 nuclei) and then direct the deuterons onto a solid or gaseou
> (a) When the resistance of an RLC series circuit that is at resonance is doubled, what happens to the power dissipated? (b) Now consider an RLC series circuit that is not at resonance. For this circuit, the initial resistance and impedance are related b
> A typical hospital accelerator built for proton beam therapy accelerates protons from rest by passing them through an electric potential difference of magnitude 75 MV. Find the speed of these protons.
> An ac series circuit containing a capacitor, inductor, and resistance is found to have a current of amplitude 0.50 A for a source voltage of amplitude 10.0 V at an angular frequency of 200.0 rad/s. The total resistance in the circuit is 15.0 Ω. (a) What
> An electron accelerator used in a hospital for cancer treatment produces a beam of electrons with kinetic energy 25 MeV. (a) What is the speed of the electrons produced by this accelerator? (b) If the end of the electron accelerator is placed 15 cm fro
