help with physics
If we continue heating a piece of initially
room-temperature metal in a dark room,
what will be its first visible color?
1. There will be no color at all.
2. Red
3. Violet
4. White
002 10.0 points
The temperature of your skin is approxi-
mately 37 C.
What is the wavelength at which the peak
occurs in the radiation emitted from your
skin?
Answer in units of nm
003 10.0 points
A quantum of electromagnetic radiation has
an energy of 0.83 keV.
What is its frequency? Planck’s constant is
6.63 × 10−34 J · s.
Answer in units of Hz
004 10.0 points
An X-ray has a wavelength of 0.0238 nm.
What is the energy of this X-ray? The
speed of light is 2.99792 × 108 m/s and
Planck’s constant is 6.62607 × 10−34 J · s.
Answer in units of eV
005 10.0 points
For the following types
radio waves
infared radiation
visible light
ultraviolet radiation
gamma radiation
of electromagnetic radiation, how do the
wavelength, frequency, and photon energy
change as one goes from the top of the list
to the bottom?
Wavelength Frequency Photon Energy
1. Increases Decreases Increases
2. Increases Increases Increases
3. Decreases Decreases Increases
4. Increases Decreases Decreases
5. Decreases Increases Increases
006 10.0 points
In the photoelectric effect, the maximum
speed of the electrons emitted by a metal sur-
face when it is illuminated by light depends
on which of the following?
I) Intensity of the light
II) Frequency of the light
III) Nature of the photoelectric surface
1. I only
2. II and III only
3. III only
4. I, II, and III
5. I and II only
007 10.0 points
The light intensity incident on a metallic sur-
face with a work function of 1.1 eV produces
photoeletrons with a maximum kinetic energy
of 2.65 eV.
If the frequency of the light is doubled,
what is the maximum kinetic energy of the
photoeletrons?
Answer in units of eV
008 10.0 points
The photoelectric effect experiment was sig-
nificant because
1. it showed us how to make an instrument
to detect light by converting photons into
brown (cb42578) – Homework 12 – appartaim – (20541) 2
electrons, ultimately leading to the invention
of the television camera.
2. it demonstrated the existence of quan-
tized states in atoms.
3. it proved that atoms cannot exist if the
rules of classical physics were obeyed on the
atomic scale.
4. it led to the development of the Heisen-
berg Uncertainty Principle, a revolutionary
development that forced us to abandon the
idea of determinacy at the atomic scale and
accept that all we can know are the probabil-
ities of future outcomes.
5. it required us to accept the fact that light
can behave like particles, in contrast to the
teachings of classical physics.
009 (part 1 of 2) 10.0 points
The work function for potassium is 2.24 eV.
If potassium metal is illuminated with light
of wavelength 320 nm, find the maximum
kinetic energy of the photoelectrons. The
speed of light is 3 × 108 m/s and Planck’s
constant is 6.62607 × 10−34 J · s .
Answer in units of eV
010 (part 2 of 2) 10.0 points
Find the cutoff wavelength.
Answer in units of nm
011 10.0 points
Calculate the de Broglie wavelength for a pro-
ton moving with a speed of 3.2 × 106 m/s.
The mass of a proton is 1.67262 × 10−27 kg
and Planck’s constant is 6.62607 × 10−34 J · s.
Answer in units of m
012 10.0 points
At the time of Rutherford’s gold leaf experi-
ment, scientists knew that negatively charged
electrons existed within the atom, but they
did not know where the positive charge
resided.
What information about the positive
charge was provided by Rutherford’s exper-
iment?
1. The positive charge must be concentrated
in a small core (the atomic nucleus).
2. The positive charge can freely move
within the atom.
3. There is no positive charge associated
with an atom.
4. The positive charge is spread throughout
the atom.
013 10.0 points
In the Bohr model of the atom, the postulate
stating that the orbital angular momentum of
the electron is quantized can be interpreted in
which of the following ways?
1. The atom is composed of a small, posi-
tively charged nucleus orbited by electrons.
2. An integral number of electron wave-
lengths must fit into the electron’s circular
orbit.
3. An electron has spin of
1
2
.
4. Only one electron can exist in each possi-
ble electron state.
5. An incident photon is completely ab-
sorbed when it causes an electron to move
to a higher energy state.
014 (part 1 of 6) 10.0 points
A hydrogen atom is in the excited state (n =
3).
Using the Bohr theory of the atom, find
the radius of the orbit. The value of ¯h is
1.05 × 10−34 J · s .
Answer in units of nm
015 (part 2 of 6) 10.0 points
Find the linear momentum of the electron.
Coulomb’s constant is 8.99 × 109 N · m2/C2 .
Answer in units of kg · m/