Questions and Answers of College Physics A Strategic Approach 2nd

The inductor in the RLC tuning circuit of an AM radio has a value of 350 mH. What should be the value of the variable capacitor in the circuit to tune the radio to 740 kHz?
A step-down transformer converts 120 V to 24 V, which is connected to a load of resistance 8.0 Ω. What is the resistance "seen" by the power supply connected to the primary coil of the transformer?
An electronics hobbyist is building a radio set to receive the AM band, with frequencies from 520 to 1700 kHz. What range variable capacitor will she need to go with a 230 μH inductor?
Light with a wavelength of 350 nm shines on a metal surface, which emits electrons. The stopping potential is measured to be 1.25 V. a. What is the maximum speed of emitted electrons? b. Calculate
The spacing between atoms in graphite is approximately 0.25 nm. What is the energy of an x-ray photon with this wave- length?
A firefly glows by the direct conversion of chemical energy to light. The light emitted by a firefly has peak intensity at a wavelength of 550 nm.a. What is the minimum chemical energy, in eV,
Your eyes have three different types of cones with maximum absorption at 437 nm, 533 nm, and 564 nm. What photon energies correspond to these wavelengths?
What is the ratio of the energy of a photon of light at the far red end of the visible spectrum (700 nm) to that of a photon at the far blue end of the visible spectrum (400 nm)?
Station KAIM in Hawaii broadcasts on the AM dial at 870 kHz, with a maximum power of 50,000 W. At maximun power, how many photons does the transmitting antenna emit each second?
550 nm is the average wavelength of visible light. a. What is the energy of a photon with a wavelength of 550 nm? b. A typical incandescent lightbulb emits about 1 J of visible light energy every
Estimate your de Broglie wavelength while walking at a speed of 1 m/s.
a. What is the speed of an electron with a de Broglie wave-length of 0.20 nm? b. What is the speed of a proton with a de Broglie wave-length of 0.20 nm?
What is the length of a box in which the minimum energy of an electron is 1.5 X 10-18 J?
Bohr did not include the gravitational force in his analysis of the hydrogen atom. Is this one of the reasons that his model of the hydrogen atom had only limited success? Explain.
The speed of an electron is known to be between 3.0 X 106 m/s and 3.2 106 m/s. Estimate the uncertainty in its position.
Rubidium atoms are cooled to 0.10 μK in an atom trap. What is their de Broglie wavelength? How many times larger is this than the 0.25 nm diameter of the atoms?
What is the kinetic energy, in eV, of an electron with a de Broglie wavelength of 1.0 nm?
The nucleus of a typical atom is 5.0 fm (1 fm = 10-5 m) in diameter. A very simple model of the nucleus is a one-dimensional box in which protons are confined. Estimate the energy of a proton in the
The allowed energies of a quantum system are 0.0 eV, 1.5 eV, 3.0 eV, and 6.0 eV. How many different wavelengths appear in the emission spectrum?
A spherical virus has a diameter of 50 nm. It is contained inside a long, narrow cell of length 1 X 10-4 m. What uncertainty does this imply for the velocity of the virus along the length of the
X rays with a wavelength of 0.0700 nm diffract from a crystal. Two adjacent angles of x-ray diffraction are 45.6° and 21.0°. What is the distance in nm between the atomic planes responsible for the
A typical incandescent lightbulb emits approximately 3 x 1018 visible-light photons per second. Your eye, when it is fully dark adapted, can barely see the light from an incandescent lightbulb 10 km
The intensity of sunlight hitting the surface of the earth on a cloudy day is about 0.50 kW/m. Assuming your pupil can close down to a diameter of 2.0 mm and that the average wavelength of visible
A red LED (light emitting diode) is connected to a battery; it carries a current. As electrons move through the diode, they jump between states, emitting photons in the process. Assume that each
An electron confined to a one-dimensional box of length 0.70 nm jumps from the n = 2 level to the ground state. What is the wavelength (in nm) of the emitted photon?
Electrons with a speed of 2.0 × 106 m/s pass through a double-slit apparatus. Interference fringes are detected with a fringe spacing of 1.5 mm. a. What will the fringe spacing be if the electrons
Electrons pass through a 1.0-μm-wide slit with a speed of 1.5 x 106 m/s. How wide is the electron diffraction pattern on a detector 1.0 m behind the slit?
a. What is the minimum energy of a 2.7 g Ping-Pong ball in a 10-cm-long box? b. What speed corresponds to this kinetic energy?
The color of dyes results from the preferential absorption of certain wavelengths of light. Certain dye molecules consist of symmetric pairs of rings joined at the center by a chain of car- bon
The two spectra shown in Figure Q29.2 belong to the same element, a fictional Element X. Explain why they are different. FIGURE Q29.2 Emission spectrum Absorption spectrum
An electron confined to a box has an energy of 1.28 eV. Another electron confined to an identical box has an energy of 2.88 eV. What is the smallest possible length for those boxes?
It can be shown that the allowed energies of a particle of mass m in a two-dimensional square box of side L are The energy depends on two quantum numbers, n and I, both of which must have an integer
Two adjacent allowed energies of an electron in a one-dimensional box are 2.0 eV and 4.5 eV. What is the length of the box?
When the electron is struck by the x-ray photon, increases. decreases.A. Its de Broglie wavelength B. Its de Broglie wavelength C. Its de Broglie wavelength stays the same.
Exposure to a sufficient quantity of ultraviolet will redden the skin, producing erythema-a sunburn. The amount of exposure necessary to produce this reddening depends on the wave- length. For a 1.0
What is the angular momentum of a hydrogen atom in (a) A 4p state (b) A 5f state? Give your answers as a multiple of h.
The Paschen series is analogous to the Balmer series, but with m = 3. Calculate the wavelengths of the first three members in the Paschen series. What part(s) of the electromagnetic spectrum are
J. J. Thomson studied the ionization of atoms in collisions with electrons. He accelerated electrons through a potential difference, shot them into a gas of atoms, then used a mass spectrometer to
For a hydrogen atom, list all possible states (n, l, m, m.) that have E = -1.51 eV.
Does each diagram in Figure Q29.12 represent a possible electron configuration of a neutral element? If so, (i) Identify the element(ii) Determine if this is the ground state or an excited state. If
A researcher observes hydrogen emitting photons of energy 1.89 eV. What are the quantum numbers of the two states involved in the transition that emits these photons?
A hydrogen atom is in the n = 3 state. In the Bohr model, how many electron wavelengths fit around this orbit?
A hydrogen atom is in its n = 1 state. In the Bohr model, what is the ratio of its kinetic energy to its potential energy?
An electron is in an f state. Can it undergo a quantum jump to an s state? A p state? A d state? Explain.
Show, by actual calculation, that the Bohr radius is 0.0529 nm and that the ground-state energy of hydrogen is -13.60 eV.
Seven possible transitions are identified on the energy level diagram in Figure Q29.20. For each, is this an allowed transition? If allowed, is it an emission or an absorption transition, and is the
List the quantum numbers of (a) All possible 3p states (b) All possible 3d states.
Predict the ground-state electron configurations of Si, Ge, and Pb.
A hydrogen atom is in the 5p state. Determine (a) Its energy. (b) Its angular momentum, (c) Its quantum number I,(d) The possible values of its magnetic quantum number m.
a. With what element is the 3s subshell first completely filled? b. With what element is the 4d subshell first half-filled?
Consider the model of nerve conduction in myelinated axons presented in the chapter. Suppose the distance between the nodes of Ranvier was halved for a particular axon.a. How would this affect the
What is the energy of a Bohr hydrogen atom with a 5.18 nm diameter?
What is the wavelength of the series limit (i.e., the shortest possible wavelength) of the Lyman series in hydrogen?
A simple atom has only two absorption lines, at 250 nm and 600 nm. What is the wavelength of the one line in the emission spectrum that does not appear in the absorption spectrum?
A simple atom has four lines in its absorption spectrum. Ignoring any selection rules, how many lines will it have in its emission spectrum?
A 2.55 eV photon is emitted from a hydrogen atom. What are the Balmer formula n and m values corresponding to this emission?
A 1.00 mW helium neon-laser emits a visible laser beam with a wavelength of 633 nm. How many photons are emitted per second?
An electron with a kinetic energy of 3.90 eV collides with a sodium atom. What possible wavelengths of light are subsequently emitted?
A 1000 W carbon dioxide laser emits an infrared laser beam with a wavelength of 10.6 μm. How many photons are emitted per second?
What is the minimum wavelength of light that can excite the 4s state of sodium?
Hydrogen gas absorbs light of wavelength 103 nm. After- ward, what wavelengths are seen in the emission spectrum?
An electron with a speed of 5.00 × 106 m/s collides with an atom. The collision excites the atom from its ground state (0 eV) to a state with an energy of 3.80 eV. What is the speed of the electron
Which has higher energy: an electron in the 4f state or an electron in the 7s state? Explain.
An insulated copper wire is wrapped around an iron nail. The resulting coil of wire consists of 240 turns of wire that cover 1.8 cm of the nail, as shown in Figure P24.57. A current of 0.60 A passes
How does the kinetic energy of the particle in Figure P24.62 change as it traverses the velocity selector?A. The kinetic energy increases. B. The kinetic energy does not change. C. The kinetic
The world's strongest magnet can produce a steady field of 45 T. If a circular wire loop of radius 10 cm were held in this magnetic field, what current would be induced in the loop?
Parts a through f of Figure Q25.3 show one or more metal wires sliding on fixed metal rails in a magnetic field. For each, determine if the induced current is clockwise, counterclockwise, or is
The rapid vibration accompanying the swimming motions of mayflies has been measured by gluing a small magnet to a swimming mayfly and recording the emf in a small coil of wire placed nearby. Explain
The power lines that run through your neighborhood carry alternating currents that reverse direction 120 times per second. As the current changes, so does the magnetic field around a line. Suppose
The magnetic flux passing through a coil of wire varies as shown in Figure Q25.8. During which time interval(s) will an induced current be present in the coil? Explain. 1/2 FIGURE Q25.8 1
Cars on the "Tower of Doom" carnival ride are dropped from a great height, giving riders a few seconds of free fall. To stop the cars, strong permanent magnets attached to the bottoms of the cars
A conducting loop around a region of strong magnetic field contains two light bulbs, as shown in Figure Q25.17. The wires connecting the bulbs are ideal. The magnetic field is increasing rapidly. a.
A magnet dropped through a clear plastic tube accelerates as expected in free fall. If dropped through an aluminum tube of exactly the same length and diameter, the magnet falls much more slowly.
Two polarizers are oriented with axes at 90°, so no light passes through the pair. A piece of plastic is placed between the two. If the plastic is stressed, by being squeezed, light that passes
Though sunlight is unpolarized, the light that reflects from smooth surfaces may be partially polarized in the direction parallel to the plane of the reflecting surface. How should the long axis of
Old-fashioned roof-mounted television antennas were designed to pick up signals across a broad frequency range. Explain why these antennas had metal bars of many different lengths.
The intensity of a beam of light is increased but the light's frequency is unchanged. As a result, which of the following (per-haps more than one) are true? Explain. A. The photons travel
The frequency of a beam of light is increased but the light's intensity is unchanged. As a result, which of the following (perhaps more than one) are true? Explain. A. The photons travel faster. B.
Arc welding uses electric current to make an extremely hot electric arc that can melt metal. The arc emits ultraviolet light that can cause sun- burn and eye damage if a welder is not wearing
A spacecraft in orbit around the moon measures its altitude by reflecting a pulsed 10 MHz radio signal from the surface. If the spacecraft is 10 km high, what is the time between the emission of the
A 6.0 mW vertically polarized laser beam passes through a polarizing filter whose axis is 75° from vertical. What is the laser-beam power after passing through the filter? A. 0.40 mW B. 1.0 mW C.
A1 x 10-3 m-3 chunk of material has a mass of 3 kg. a. What is the material's density? b. Would a 2 x 10-3 m3 chunk of the same material have the same mass? Explain. c. Would a 2 x 10-3 m3 chunk
In the circuit shown in Figure Q23.6, bulbs A and B are glowing. Then the switch is closed. What happens to each bulb? Does it get brighter, stay the same, get dimmer, or go out? Explain.
One way to find out if a wire has corroded is to measure its resistance. Explain why the resistance of a wire increases if it becomes corroded.
The current in a circuit with only one battery is 2.0 A. Figure P23.9 shows how the potential changes when going around the circuit in the clockwise direction, starting from the lower left corner.
The three bulbs in Figure Q23.13 are identical. Rank the bulbs from brightest to dimmest. Explain. A FIGURE Q23.13 с B
An 80-cm-long wire is made by welding a 1.0-mm-diameter, 20-cm-long copper wire to a 1.0-mm-diameter, 60-cm-long iron wire. What is the resistance of the composite wire?
The four bulbs in Figure Q23.14 are identical. Rank the bulbs from brightest to dimmest. Explain. D e B FIGURE Q23.14
You have a collection of 1.0 kΩ resistors. How can you connect four of them to produce an equivalent resistance of 0.25 kΩ?
Figure Q23.15 shows five identical bulbs connected to a battery. All the bulbs are glowing. Rank the bulbs from brightest to dimmest. Explain. Switch FIGURE Q23.23 (2) Bulb A Bulb B (e)
A voltmeter is (incorrectly) inserted into a circuit as shown in Figure Q23.20.Figure Q23.20. a. What is the current in the circuit? b. What does the voltmeter read? c. How would you change the
You have six 1.0 kΩ resistors. How can you connect them to produce a total equivalent resistance of 1.5 kΩ?
An ammeter is (incorrectly) inserted into a circuit as shown in Figure Q23.21. a. What is the current through the 5.0 Ω resistor? b. How would you change the circuit to correctly connect the
What are the resistance R and the emf of the battery in Figure P23.23? 3.0 A FIGURE P23.23 R 2.0 A wwwwwww 10 2
A charged capacitor could be connected to two identical resistors in either of the two ways shown in Figure Q23.25. Which configuration will discharge of the capacitor in the shortest time once the
A flashing light is controlled by the charging and discharging of an RC circuit. If the light is flashing too rapidly, describe two changes that you could make to the circuit to reduce the flash rate.
In the circuit of Figure P23.28, what are the values of ΔV14, ΔV 24, and ΔV 34? FIGURE P23.28 10 V Μ 500 Μ 5.0Ω 5.00 Μ 10 Ω Μ 10 Ω 3 Μ 50Ω
A device to make an electrical measurement of skin moisture has electrodes that form two plates of a capacitor; the skin is the dielectric between the plates. Adding moisture to the skin means adding
For the circuit shown in Figure P23.29, find the current through and the potential difference across each resistor. Place your results in a table for ease of reading. 12 V 3.002 ww ww 16 Ω ww FIGURE
Adding a myelin sheath to an axon results in faster signal propagation. It also means that less energy is required for a signal to propagate down the axon. Explain why this is so.

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