Physics Test 3
Convert 100 eV to Joules. 1.60 x 10^(-17) Joules 1.60 x 10^(-18) Joules 1.60 x 10^(-19) Joules 3.20 x 10^(-17) Joules
1.60 x 10^(-17) Joules
A radioactive sample has a half life of 1 year. How much of the original sample will be left at the end of the second year? 1/4 1/8 1/16 none.
1/4
The half life of carbon 14 is 5730 years. If a 1-gram sample of old carbon is 1/8 as radioactive as 1-gram of a current sample, then the age of the old sample is about 5,730 years. 11,500 years. 28,600 years. 17,200 years.
17,200 years.
A certain radioactive isotope placed near a Geiger counter registers 160 counts per second. Eight hours later, the counter registers 10 counts per second. What is the half life of the isotope? 8 hours. 4 hours. 6 hours. 2 hours.
2 hours.
A Geiger counter placed 1 meter from a point source of radiation registers 100 counts per second. If the Geiger counter is moved closer - to 0.5 meter from the source, what will the count rate be? 400 counts/s. 200 counts/s. 1600 count/s. 100 counts/s.
400 counts/s.
A particular (hypothetical) atom has 3 energy levels at -100 eV (ground state), -50 eV and -25 eV. What is the energy in eV of the highest frequency photon that can be emitted by this atom? 150 eV 50 eV 75 eV 100 eV
75 eV
When radium (A = 88) emits an alpha particle, the resulting nucleus has atomic number 92 86 88 90
86
When thorium (A = 90) emits a beta particle, the resulting nucleus has atomic number 88 90 91 89
91
Radioactive isotope A has a half-life of one year, while radioactive isotope B has a half-life of one day. If equal numbers of atoms of each are present, which will give the highest reading on a Geiger counter? B both the same. A
B
In order for an atom to decay to an element which is one greater in atomic number, it can emit all of these. one alpha particle and 3 beta particles. one beta particle. one positron and 2 beta particles.
all of these.
X-rays are short wavelength photons. all of these. high energy photons. high frequency electromagnetic waves.
all of these.
An atom that emits a certain frequency of light is an absorber of all frequencies. transparent to all frequencies. not likely to absorb that same frequency. an absorber of the same frequency.
an absorber of the same frequency.
When an alpha particle is ejected from a nucleus, the nucleus then has less neither of these. charge. both of these. mass.
both of these.
The sources of X rays and gamma rays, respectively, are the atomic nucleus and electron clouds. electron clouds and the atomic nucleus. both electron clouds. both the atomic nucleus
electron clouds and the atomic nucleus.
Once an alpha particle is outside the nucleus it is quickly bound to a neighboring nucleus. electrostatically repelled. free to wander about the nucleus. radioactive.
electrostatically repelled.
When a gamma ray is emitted by a nucleus, the nucleus then has appreciably less none of these. energy. charge. mass.
energy.
The energy of a photon depends on its amplitude. frequency. speed . all of these.
frequency.
Generally speaking, the larger a nucleus is, the greater its instability. neither of these. stability
instability.
Light is emitted when an electron neither of these. both of these. is boosted to a higher energy level. makes a transition to a lower energy level.
makes a transition to a lower energy level.
Different isotopes of an element have different numbers of electrons. neutrons. photons. protons.
neutrons.
The atomic mass number of an element is the same as the number of its protons. nucleons. neutrons. none of these.
nucleons.
Electrons with the greater potential energies with respect to the atomic nucleus are inner electrons. outer electrons. both the same, actually.
outer electrons.
The atomic number of an element is the same as the number of its none of these. electrons. neutrons. protons.
protons.
To say that energy levels in an atom are discrete is to say the energy levels are well defined and separated from one another by the same energy increments. continuous. separate from one another. not clearly defined.
separate from one another.
The main reason electrons occupy discrete orbits in an atom is because electric forces act over quantized distances. the circumference of each orbit is an integral multiple of electron wavelengths. none of these. electrons are basically discrete particles.
the circumference of each orbit is an integral multiple of electron wavelengths.
Characteristic radiation refers to the X-rays emitted by an atom due to absorption of photons. the loss of KE from electrons striking the atom. The heat generated in the X-ray tube. transitions between energy levels in the atom.
transitions between energy levels in the atom.
The highest frequency light of those below is violet. green. red. yellow.
violet.