Questions and Answers of Physics Everyday Phenomena

Can we make holograms using an ordinary light source rather than a laser? Explain.
Does the production of a hologram involve the interference of light waves? Explain.
Are liquid crystals fluids or solids? Explain.
Are superfluids the same as superconductors? Explain.
With the high-temperature superconductors currently available, can we build superconducting magnets that will operate in a superconducting mode at room temperature? Explain.
Does a superconductor have zero resistance only above a certain critical temperature? Explain.
In making ever-smaller electronic instruments, do integrated circuits have an advantage over the use of separate transistors and diodes? Explain.
What property of transistors makes them useful for amplifying an electrical signal? Explain.
Can a diode be made from material that is doped with just one type of impurity atom? Explain.
Does the direction in which the battery is connected to a diode affect the amount of electric current that will flow through the diode? Explain.
Does doping of silicon with gallium make the resulting semiconductor an n-type or p-type semiconductor? Explain.
Is the electrical resistance of a semiconductor such as silicon increased when we dope it with impurity atoms of arsenic? Explain.
Is it necessary to know anything about very small entities scale phenomena such as the beginning of the universe? Explain.
Does the term Big Bang refer to explosions of individual stars? Explain.
What force is responsible for the formation of atoms from individual nuclei and electrons? What force is responsible for the condensation of individual atoms into stars? Explain.
Is the Milky Way a cloud of interstellar gases? Explain.
Is our own sun part of a galaxy? Explain.
How do we know that the universe is expanding? Explain.
Why do physicists propose spending large amounts of money to build new particle accelerators? How can we justify these large expenditures? Explain.
Which fundamental force of nature is the most difficult to incorporate into a completely unified field theory? Explain.
Why are high energies required to produce particles with larger masses than protons or neutrons? Explain.
Are baryons and mesons made up of the same number of quarks? Explain.
Are quarks constituents of electrons? Explain.
Do we now consider protons to be elementary particles that do not have any underlying structure? Explain.
Are leptons generally heavier than protons or neutrons? Explain.
Using the diagram shown in figure 20.13, derive the time dilation formula. The steps are:a. From the symmetry of the diagram, we assume that the total time measured by the Earth observer is twice the
Suppose that a beaker of water contains 1 kg (1000 g) of water. Heat is added to the water to raise its temperature from 0°C to 100°C.a. How much heat energy in joules must be added to the water to
Suppose that an astronaut travels to a distant star and returns to Earth. Except for brief intervals of time when he is accelerating or decelerating, his spaceship travels at the incredible speed of
Nuclear power has been a constant source of controversy over the last few decades. Although the use of nuclear power has grown during this time, we still get over half of our electric power by
Consider the fusion reaction: 1H2 + 1H2 ⇒ 2He3 + 0n1. From tables of nuclear masses, we can find the masses for the reactants and products in this reaction: H2 2.014 102 u He3 3.016 029 u n 1.008
Uranium and thorium are the radioactive elements found in some abundance in the Earth’s crust. As each isotope of these elements decays, new radioactive elements are created that have much shorter
Using the periodic table found in the inside back cover, we can get some idea of how the number of neutrons increases compared to the number of protons as the atomic number increases. By rounding the
Suppose that two deuterium nuclei (1H2) combine in a fusion reaction in which a neutron is emitted. Complete the reaction equation and identify the resulting nucleus.1H2 + 1U2 ⇒ ? + 0n1
Suppose that we discover that one of the fission fragments for a given fission reaction of uranium-235 is tin-130 and that four neutrons are emitted in this reaction. Complete the reaction equation
How many half-lives must go by for the radioactivity of a given isotope to drop toa. One-sixteenth (1⁄16) of its original value?b. One-sixty-fourth (1⁄64) of its original value?
When we measure the rate of radioactivity of a given isotope 18 days after making an initial measurement, we discover that the rate has dropped to one-eighth of its initial value. What is the
Suppose that we have 10 000 atoms of a radioactive substance with a half-life of 30 minutes.a. How many atoms of that element remain after 2 hours?b. How many atoms remain after 4 hours?
Nitrogen-13 is a radioactive isotope of nitrogen that undergoes positive beta decay in which a positive electron (or positron) is emitted. Complete the reaction equation and identify the daughter
The fission fragment iodine-131 undergoes negative beta decay. Complete the reaction equation and identify the daughter nucleus.53I131 ⇒ ? + -1e0 + 0v-0
Thorium-232 undergoes alpha decay. Complete the reaction equation for this decay and identify the daughter nucleus.90Th232 ⇒ ? + α
Strontium-90 is a radioactive isotope of strontium, which has an atomic number of 38. How many protons and how many neutrons are present in the nucleus of this isotope?
A certain isotope has 13 protons and 14 neutrons in its nucleus. Identify the element involved and write its symbol in the standard notation including the atomic and mass numbers.
93Np239 is an isotope produced in nuclear reactors.a. How many protons are in the nucleus of this isotope?b. How many neutrons are in the nucleus of this isotope?
Sodium has an atomic number of 11 and an atomic weight of approximately 23. How many neutrons would you expect to find in the nucleus of the most common isotope of sodium?
Which can produce larger yields of energy, a fission weapon or a fusion weapon? Explain.
Do we currently have commercial nuclear reactors that use nuclear fusion as their energy source? Explain.
Is nuclear fission the main process involved in the energy generated in the sun? Explain.
How does nuclear fusion differ from nuclear fission? Explain.
What was the purpose of the nuclear reactors built at Hanford, Washington, during World War II? Explain.
In Fermi’s original experiments in which he bombarded uranium samples with neutrons, he was trying to produce new elements heavier than uranium. Is it possible to do so? Explain.
If plutonium and uranium are removed from the spent fuel of a nuclear reactor, will the remaining nuclear wastes need to be stored for thousands of years before they become nonradioactive? Explain.
If a reactor goes subcritical, will the chain reaction speed up? Explain.
Will a reactor that uses ordinary water as the moderator be able to operate using unenriched uranium as a fuel? Explain.
If you wanted to slow down the chain reaction in a nuclear reactor, would you remove or insert the control rods? Explain.
Do the control rods in a nuclear reactor absorb or emit neutrons? Explain.
What is the function of the moderator in a nuclear reactor? Explain why the moderator is needed to obtain a chain reaction using natural uranium.
What property of the fission reaction leads to the possibility of a chain reaction? Explain.
The most common isotope of uranium is uranium-238. Is this the isotope that is most likely to undergo fission? Explain.
Suppose that you light a match to a mixture of oxygen and hydrogen, which then reacts explosively to form water. Is this a chemical reaction or a nuclear reaction? Explain.
Why do we expect fission fragments to have higher neutron numbers than stable isotopes of the same element and, therefore, to be radioactive? Explain.
Chemical reactions and nuclear reactions can both release energy. On the average, would you expect the energy released per unit of mass in a chemical reaction to be greater than, equal to, or less
In chemical reactions, the individual elements present in the reactants are the same as in the products of the reaction. Is this also true in a nuclear reaction? Explain.
In a time equal to two half-lives of a radioactive isotope, would you expect all of that isotope to have decayed? Explain.
Do all radioactive substances decay at the same rate? Explain.
In gamma decay, do we expect the atomic number of the daughter nucleus to be equal to, greater than, or less than the atomic number of the decaying isotope? Explain.
What is a neutrino and why did scientists believe in its existence long before it was ever detected? Explain.
In beta decay, do we expect the atomic number of the daughter nucleus to be equal to, greater than, or less than the atomic number of the isotope undergoing decay? Explain.
In alpha decay, do we expect the atomic number of the daughter nucleus to be equal to, greater than, or less than the atomic number of the isotope undergoing decay? Explain.
In a nuclear reaction, can the total mass of the products of the reaction be less than the total mass of the reactants? Explain.
Why is the atomic weight of chlorine, as determined from chemical experiments, not a whole-number multiple of the atomic weight of hydrogen? Explain.
Which number, the mass number or the atomic number, determines the chemical properties of an element? Explain.
Is it possible for atoms of the same chemical element to have different chemical properties? Explain.
Is it possible for two atoms of the same chemical element to have different masses? Explain.
When beryllium is bombarded with alpha particles, a very penetrating radiation is emitted from the beryllium sample. Does this radiation consist of X rays? Explain.
In 1919, Rutherford bombarded a sample of nitrogen gas with a beam of alpha particles.a. In addition to alpha particles, what other particle emerged from the nitrogen gas in this experiment?b. What
Suppose that an electron (m = 9.1 x 10-31 kg) is moving with a velocity of 1500 m/s.a. What is the momentum of this electron?b. What is the de Broglie wavelength of this electron?c. How does this
When an electron is removed completely from an atom, we say that the atom is ionized. An ionized atom has a net positive charge since an electron has been removed.a. From the energy-level diagram in
Study the energy-level diagram shown in figure 18.20. The Balmer series of spectral lines all involve transitions to the n = 2 energy level, and the Lyman series in the ultraviolet involves
An electron beam in a cathode-ray tube passes between two parallel plates that have a voltage difference of 300 V across them and are separated by a distance of 2 cm, as shown in the diagram.a. In
An electron in the hydrogen atom jumps from an orbit in which the energy is 1.89 eV higher than the energy of the final lower-energy orbit.a. What is the frequency of the photon emitted in this
Suppose that a photon has an energy of 3.6 x 10-19 J.a. What is the frequency of this photon? (h = 6.626 x 10-34 J·s)b. What is the wavelength of this photon?
Suppose that a photon has a wavelength of 650 nm (red).a. What is the frequency of this photon?b. What is the energy of this photon in joules?
Using the Rydberg formula, find the wavelength of the spectral line for which m = 3 and n = 1. Would this line be visible to the unaided eye? Explain.
Suppose that a microscope has an objective lens with a focal length of 0.8 cm and an eyepiece lens with a focal length of 2.5 cm. The object is located 1.0 cm in front of the objective lens.a.
An object 2 cm tall is located 30 cm from a concave mirror with a focal length of 15 cm. Since the focal length is half the radius of the curvature, the object is located at the center of curvature
An object with a height of 2.5 cm lies 10 cm in front of a lens with a focal length of 6 cm.a. Using the object-image distance formula, calculate the image distance for this object.b. What is the
An object is located at the focal point of a positive lens with a focal length of 12 cm.a. What is the image distance predicted by the object image distance formula?b. Trace two rays to confirm the
A fish is viewed through the glass wall of a fish tank. The index of refraction of the glass is 1.5 and that of the water in the tank is 1.33. The fish lies a distance of 6 cm behind the glass. Light
A telescope that produces an overall angular magnification of 20x uses an eyepiece lens with a focal length of 2.5 cm. What is the focal length of the objective lens?
A telescope has an objective lens with a focal length of +40 cm and an eyepiece with a focal length of +2.5 cm. What is the angular magnification produced by this telescope?
The objective lens of a telescope has a focal length of 1.0 m. An object is located at a distance of 10 m from the lens.a. At what distance from the objective lens is the image formed by this lens?b.
The objective lens of a microscope has a focal length of 0.4 cm. An object on the microscope slide is placed at a distance of 0.5 cm from the lens.a. At what distance from the lens is the image
A convex mirror used in a store aisle has a focal length of -60 cm. A person in the aisle is 3.0 m from the mirror.a. How far from the mirror is the image of this object?b. If the person is 1.8 m
A convex mirror has a focal length of -10 cm. An object is located 10 cm from the surface of the mirror.a. How far from the mirror is the image of this object?b. Is the image real or virtual, upright
A concave mirror has a focal length of 10 cm. An object is located 30 cm from the surface of the mirror.a. How far from the mirror is the image of this object?b. Is the image real or virtual, upright
A concave mirror has a focal length of 12 cm. An object is located 6 cm from the surface of the mirror.a. How far from the mirror is the image of this object?b. Is the image real or virtual, upright
A magnifying glass with a focal length of +4 cm is placed 2 cm above a page of print.a. At what distance from the lens is the image of the page?b. What is the magnification of this image?
A negative lens has a focal length of -10 cm. An object is located 20 cm from the lens.a. How far from the lens is the image?b. Is the image real or virtual, erect or inverted?
A positive lens forms a real image of an object placed 8 cm to the left of the lens. The real image is found 16 cm to the right of the lens. What is the focal length of the lens?
A positive lens has a focal length of 12 cm. An object is located at a distance of 3 cm from the lens.a. How far from the lens is the image?b. Is the image real or virtual, erect or inverted?c. Trace

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