Questions and Answers of College Physics A Strategic Approach 2nd

The Channel Tunnel, or “Chunnel,” which runs under the English Channel between Great Britain and France is 31 mi long. (There are actually three separate tunnels.) A shuttle train that carries
What kind of decay, if any, would you expect for the nuclei with the energy-level diagrams shown in Figure Q30.16? Energy (a) 22 22- Neutrons FIGURE Q30.16 Protons Energy
A patient's tumor is irradiated with gamma rays from an external source. Afterward, is his body radioactive? Explain.
It's possible that a bone tumor will not show up on an x-ray image but will show up in a gamma scan. Explain why this is so.
Four radiation doses are as follows: Dose A is 10 rad with an RBE of 1, dose B is 20 rad with an RBE of 1, dose C is 10 rad with an RBE of 2, and dose D is 20 rad with an RBE of 2. a. Rank in order,
Two different sources of radiation give the same dose equivalent in Sv. Does this mean that the radiation from each source has the same RBE? Explain.
Some types of MRI can produce images of resolution and detail similar to PET. Though the images are similar, MRI is generally preferred over PET for studies of brain function involving healthy
Sulfur colloid particles tagged with 99Tc are taken up and retained by cells in the liver and spleen. A patient is suspected of having a liver tumor that would destroy these cells. Explain how a
The first two letters in the acronym SPECT, which describes a nuclear imaging technique, stand for "single photon." Is a SPECT done with a gamma emitter or a positron emitter?
A certain watch's luminous glow is due to zinc sulfide paint that is energized by beta particles given off by tritium, the radioactive hydrogen isotope 3H, which has a half-life of 12.3 years. This
A significant fraction of the radiation dose you will receive during your life comes from radioactive materials in your body. The most important source of this radiation is the potassium isotope 40K,
Oil and coal generally contain no measurable 14C. What does this tell us about how long they have been buried?
Four samples each contain a single radioactive isotope. Sample A has 1 mol of matter and an activity of 100 Bq. Sample B has 10 mol and 100 Bq, sample C has 100 mol and 100 Bq, and sample D has 100
Figure Q30.7 shows how the number of nuclei of one particular isotope varies with time. What is the half-life of the nucleus? N 1,000,000- 250,000- 0+ 0 FIGURE Q30.7 8 days
A radioactive sample has a half-life of 10 s. 10,000 nuclei are present at t = 20 s. a. How many nuclei were there at t = 0 s? b. How many nuclei will there be at t = 40 s?
For each nuclear energy-level diagram in Figure Q30.6, state whether it represents a nuclear ground state, an excited nuclear state, or an impossible nucleus. Energy (a) 22 + 22- Neutrons
A sample contains a mix of isotopes of an element. Using a spectrometer to measure the spectrum of emitted light will not reveal the mix of isotopes; analyzing the sample with a mass spectrometer
A "soft x-ray" photon with an energy of 41.8 eV is absorbed by a hydrogen atom in its ground state, knocking the atom's electron out. What is the speed of the electron as it leaves the atom? A. 1.84
Atom A has a larger atomic mass than atom B. Does this mean that atom A also has a larger atomic number? Explain.
The angular momentum of an electron in a Bohr hydrogen atom is 3.18 × 10-34 kg. m2/s. What is the atom's energy?A. - 13.60 eV B. -6.73 eV C. -3.40 eVD. -1.51 eVE. -0.47 eV
A glass tube contains 2 x 1011 atoms, some of which are in the ground state and some of which are excited. Figure Q29.22 shows the populations for the atoms' three energy levels. Is it possible for
An atom emits a photon with a wavelength of 275 nm. By how much does the atom's energy change?A. 0.72 eV B. 1.06 eV C. 2.29 eVD. 3.06 eVE. 4.51 eV
What is the length of a box in which the difference between an electron's first and second allowed energies is 1.0 X 10-19 J?
A silicon solar cell looks like a battery with a 0.50 V terminal voltage. Suppose that 1.0 W of light of wavelength 600 nm falls on a solar cell and that 50% of the photons give their energy to
The wavelength of the radiation in a microwave oven is 12 cm. How many photons are absorbed by 200 g of water as it's heated from 20°C to 90°C?
The human body emits thermal electromagnetic radiation, as we've seen. Assuming that all radiation is emitted at the wave- length of peak intensity, for a skin temperature of 33°C and a surface area
Figure P28.39 is an energy-level diagram for a quantum system. What wavelengths appear in the system's emission spectrum? FIGURE P28.39 n=3 n = 2 n = 1 -E₂ = 4.0 eV -E₂ = 1.5 eV -E₁ = 0.0 eV
The allowed energies of a quantum system are 0.0 eV, 4.0 eV, and 6.0 eV.a. Draw the system's energy-level diagram. Label each level with the energy and the quantum number. b. What wavelengths appear
The allowed energies of a quantum system are 1.0 eV, 2.0 eV, 4.0 eV, and 7.0 eV. What wavelengths appear in the system's emission spectrum?
Dinoflagellates are single-cell creatures that float in the world's oceans; many types are bioluminescent. When disturbed by motion in the water, a typical bioluminescent dinoflagellate emits
When an ultraviolet photon is absorbed by a molecule of DNA, the photon's energy can be converted into vibrational energy of the molecular bonds. Excessive vibration damages the molecule by causing
An LC circuit is built with a 20 mH inductor and an 8.0 μF capacitor. The current has its maximum value of 0.50 A at t = 0 s. How long does it take until the capacitor is fully charged?
In a nuclear magnetic resonance spectrometer, a 15 mH coil is designed to detect an emf oscillating at 400 MHz. The coil is part of an RLC circuit. What value of the capacitance C should be used so
Your computer has a built-in "surge protector." A surge is a sudden increase in voltage on the power line. This causes a rapid "current spike" that can destroy sensitive electronic components. After
Your cell phone charger plugs into an AC electric outlet. A typical charger has a two-prong plug. Either prong can go in the hot side of the outlet; that is, you can reverse the plug and the charger
A circuit breaker won't keep you from getting a shock; a GFI will. Explain why this is so.
An 1.1-m-diameter MRI solenoid with a length of 2.4 m has a magnetic field of 1.5 T along its axis. If the current is turned off in a time of 1.2 s, what is the induced emf in one turn of the
a. A circular loop antenna has a diameter of 20 cm. If the plane of the loop is perpendicular to the earth's 50 μT magnetic field, what is the flux through the loop? b. What is the flux if the loop
While using a dimmer switch to investigate a new type of incandescent light bulb, you notice that the light changes both its spectral characteristics and its brightness as the voltage is
The intensity of electromagnetic radiation from the sun reaching the earth's upper atmosphere is 1.37 kW/m3. Assuming an average wavelength of 680 nm for this radiation, find the number of photons
A scalloped hammerhead shark swims at a steady speed of 1.5 m/s with its 85-cm-wide head perpendicular to the earth's 50 μT magnetic field. What is the magnitude of the emf induced between the two
What is the smallest box in which you can confine an electron if you want to know for certain that the electron's speed is no more than 10 m/s?
Two wires carry equal and opposite currents, as shown in Figure Q24.35. At a point directly between the two wires, the field is A. Directed up, toward the top of the page. B. Directed down, toward
Figure P25.4 shows a 15-cm-long metal rod pulled along two frictionless, conducting rails at a constant speed of 3.5 m/s. The rails have negligible resistance, but the rod has a resistance of 0.65
A 50 g horizontal metal bar, 12 cm long, is free to slide up and down between two tall, vertical metal rods that are 12 cm apart. A 0.060 T magnetic field is directed perpendicular to the plane of
The circuit of Figure P25.17 is a square 5.0 cm on a side. The magnetic field increases steadily from 0 T to 0.50 T in 10 ms. What is the current in the resistor during this time? 9.0V 2002 www
A microwave oven operates at 2.4 GHz with an intensity inside the oven of 2500 W/m2. What are the amplitudes of the oscillating electric and magnetic fields?
The maximum allowed leakage of microwave radiation from a microwave oven is 5.0 mW/cm2. If microwave radiation out- side an oven has the maximum value, what is the amplitude of the oscillating
At what distance from a 10 W point source of electromagnetic waves is the electric field amplitude.(a) 100 V/m(b) 0.010 V/m?
A 200 mW horizontally polarized laser beam passes through a polarizing filter whose axis is 25° from vertical. What is the power of the laser beam as it emerges from the filter?
The polarization of a helium-neon laser can change with time. The light from a 1.5 mW laser is initially horizontally polarized; as the laser warms up, the light changes to be vertically polarized.
What is the energy (in eV) of a photon of visible light that has a wavelength of 500 nm?
What is the energy (in eV) of an x-ray photon that has a wavelength of 1.0 nm?
What is the wavelength of a photon whose energy is twice that of a photon with a 600 nm wavelength?
The thermal emission of the human body has maximum intensity at a wavelength of approximately 9.5 μm. What photon energy corresponds to this wavelength?
The spectrum of a glowing filament has its peak at a wavelength of 1200 nm. What is the temperature of the filament, in °C?
A magnet and a coil are oriented as shown in Figure P25.50. The magnet is moved rapidly into the coil, held stationary in the coil for a short time, and then rapidly pulled back out of the coil.
A wire loop with an area of 0.020 m2 is in a magnetic field of 0.30 T directed at a 30° angle to the plane of the loop. If the field drops to zero in 45 ms, what is the average induced emf in the
A 20 cm length of 0.32-mm-diameter nichrome wire is welded into a circular loop. The loop is placed between the poles of an electromagnet, and a field of 0.55 T is switched on in a time of 15 ms.
A TMS (transcranial magnetic stimulation) device creates very rapidly changing magnetic fields. The field near a typical pulsed-field machine rises from 0 T to 2.5 T in 200 μs. Suppose a technician
The filament in the center of a 100 W incandescent bulb emits approximately 4.0 W of visible light. If you assume that all of this light is emitted at a single wavelength, estimate the electric and
A LASIK vision correction system uses a laser that emits 10-ns-long pulses of light, each with 2.5 mJ of energy. The laser is focused to a 0.85-mm-diameter circle. (a) What is the average power of
A new cordless phone emits 4.0 mW at 5.8 GHz. The manufacturer claims that the phone has a range of 100 feet. If we assume that the wave spreads out evenly with no obstructions, what is the electric
Gamma rays with the very high energy of 2.0 × 1013 eV are occasionally observed from distant astrophysical sources. What are the wavelength and frequency corresponding to this photon energy?
Identical resistors are connected to separate 12 V AC sources. One source operates at 60 Hz, the other at 120 Hz. In which circuit, if either, does the resistor dissipate the greater average power?
Consider the three circuits in Figure Q26.2. Rank in order, from largest to smallest, the average total powers P1 to P3 dissipated by all the resistors in each circuit. Explain. ww R FIGURE
Lightbulbs in AC circuits "flicker" in intensity, though the flickering is too fast for your eyes to sense it. If a light bulb is connected to a 120 V/60 Hz power supply, how many times a second does
A household wall outlet can provide no more than 15 A, but you can use this outlet to power an electric soldering iron that drives 150 A through the metal tip. How is this possible?
Figure Q26.6 shows three wires wrapped around an iron core. The number of turns and the directions of the windings in the figure should be care- fully noted. At one particular instant, VA - VB = 20
A 12 V DC power supply is connected to the primary coil of a transformer. The primary coil has 100 turns and the secondary coil has 200. What is the rms voltage across the secondary?
A toaster oven is rated at 1600 W for operation at 120 V/60 Hz. a. What is the resistance of the oven heater element? b. What is the peak current through it? c. What is the peak power dissipated
A 100 Ω resistor is connected to a 120 V/60 Hz power line. What is its average power loss?
Women usually have higher resistance of their arms and legs than men. might you expect to see this variation in resistance?
A generator produces 40 MW of power and sends it to town at an rms voltage of 75 kV. What is the rms current in the trans- mission lines?
Soles of boots that are designed to protect workers from electric shock are rated to pass a maximum rms current of 1.0 mA when connected across an 18,000 V AC source. What is the minimum allowed
The primary coil of a transformer is connected to a 120 V/60 Hz wall outlet. The secondary coil is connected to a lamp that dissipates 60 W. What is the rms current in the primary coil?
New homes are required to have GFI-protected outlets in bath- rooms, kitchens, and any outdoor locations. Why is GFI protection required in these locations but not, say, in bedrooms?
A soldering iron uses an electric current in a wire to heat the tip. A transformer with 100 turns on the secondary coil provides 50 W at an rms voltage of 24 V.a. What is the resistance of the wire
A power pack charging a cell phone battery has an output of 0.40 A at 5.2 V (both rms). What is the rms current at the 120 V/60 Hz wall outlet where the power pack is plugged in?
A neon sign transformer has a 450 W AC output with an rms voltage of 15 kV when connected to a normal household outlet. There are 500 turns of wire in the primary coil. a. How many turns of wire
Consider the four circuits in Figure Q26.15. Rank in order, from largest to smallest, the capacitive reactances (XC)1, to (Xc)4. Explain. 100 Hz 2 μF 1 FIGURE Q26.15 100 Hz 1 μF 2 50 Hz 4 μF 3 200
The "power cube" transformer for a portable CD player has an output of 4.5 V and 600 mA (both rms) when plugged into a 120 V/60 Hz outlet. a. If the primary coil has 400 turns of wire, how many
A science hobbyist has purchased a surplus power-pole trans- former that converts 7.2 kV from neighborhood distribution lines into 120 V for homes. He connects the transformer "back- ward," plugging
The wiring in the wall of your house to and from an outlet has a total resistance of typically 0.10 Ω. Suppose a device plugged into a 120 V outlet draws 10.0 A of current. a. What is the voltage
An inductor is plugged into a 120 V/60 Hz wall outlet in the U.S. Would the peak current be larger, smaller, or unchanged if this inductor were plugged into a wall outlet in a country where the
The following appliances are connected to a single 120 V, 15 A circuit in a kitchen: a 330 W blender, a 1000 W coffeepot, a 150 W coffee grinder, and a 750 W microwave oven. If these are all turned
A 60 W (120 V) night light is turned on for an average 12 hr a day year round. What is the annual cost of electricity at a billing rate of $0.10/kWh?
Suppose you leave a 110 W television and two 100 W light- bulbs on in your house to scare off burglars while you go out dancing. If the cost of electric energy in your town is $0.12/kWh and you stay
The manufacturer of an electric table saw claims that it has a 3.0 hp motor. It is designed to be used on a normal 120 V outlet with a 15 A circuit breaker. Is this claim reasonable? Explain.
The tuning circuit in a radio uses an RLC circuit. Will adjusting the resistance have any effect on the resonance frequency?
If you touch the terminal of a battery, the small area of contact means that the skin resistance will be relatively large; 50 kΩ is a reasonable value. What current will pass through your body if
A person standing barefoot on the ground 20 m from the point of a lightning strike experiences an instantaneous potential difference of 300 V between his feet. If we assume a skin resistance of 1.0
Electrodes used to make electrical measurements of the body (such as those used when recording an electrocardiogram) use a conductive paste to reduce the skin resistance to very low values. If you
A transformer has 1000 turns in the primary coil and 100 turns in the secondary coil. If the primary coil is connected to a 120 V outlet and draws 0.050 A, what are the voltage and current of the
A fisherman has netted a torpedo ray. As he picks it up, this electric fish creates a short-duration 50 V potential difference between his hands. His hands are wet with salt water, and so his skin
An AC source is connected to a series combination of a light-bulb and a variable inductor. If the inductance is increased, the bulb's brightness.A. Increases. B. Decreases. C. Does not change.
A 20 μF capacitor is connected across an AC generator that produces a peak voltage of 6.0 V. The peak current is 0.20 A. What is the oscillation frequency in Hz?
The peak current through a capacitor is 8.0 mA when connected to an AC source with a peak voltage of 1.0 V. What is the capacitive reactance of the capacitor?
The peak current through an inductor is 12.5 mA when connected to an AC source with a peak voltage of 1.0 V. What is the inductive reactance of the inductor?
The superconducting magnet in a magnetic resonance imaging system consists of a solenoid with 5.6 H of inductance. The solenoid is energized by connecting it to a 1.2 V DC power sup- ply. Starting

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