Physics Modern Physics Level: Misc Level
what is the wavelength of a photon that has the same frequency as an electron( mass is 9.11x 10 to the -31 kg) traveling at 2 x10 to the 6th m/sec?
Physics Modern Physics Level: Misc Level
Hydrogen atoms are usually found in the ground state, that is, the electron is in the n= 1 level . what wavelength light striking the atom will excite it to the n= 2 level?
Physics Modern Physics Level: Misc Level
A particle is accelerated through 200 V. Find its speed and de Broglie wavelength if is a) an electron b)a proton
Physics Modern Physics Level: Misc Level
The photoelectric threshold wavelength for pure sodium metal is 546 nm. How much energy (in electronvolts ) is needed to tear an electron away from this metal?
Physics Modern Physics Level: Misc Level
A certain radio station radiates 5000 w of power at a frequency of 1.2 x 10 to the 6th Hz a) what energy photons does the station radiate? b) How many photons does it send out each second?
Physics Modern Physics Level: Misc Level
In present -day nuclear accelerators, protons can be accelerated through 10 to the 9th power V. a) what is the ratio m/mo for such a proton ? b)How fast in comparison to c, is the proton moving?
Physics Modern Physics Level: University
Mass Energy RelationshipA photon ( traveling in the +X direction) strikes a stationary electron and recoils back in the direction it came from ( -X). What direction must the electron be traveling in after the collision and why?
Physics Modern Physics Level: University
Mass Energy Relationship1 kg of gasoline when burned in oxygen will give off about 4 x 10^7 joules of heat. According to Einstein any mass has an equivalent energy of E = mc^2. How many kgs of gasoline would have to burn ( with oxygen) to make the same amount of energy that Einsteins theory predicts that a single kg is equivalent to?
Physics Modern Physics Level: University
Time DialationWhen people are traveling at different speeds their clocks appear to run at different rates from the perspective of the other person. If one person is on a stationary platform while the other is on a ship moving rapidly past the platform whose clock is running correctly?
Physics Modern Physics Level: University
Theory of relativityA nearby star is 4.3 light years away. If a rocket leaves for that star and travels at a speed of .98 times the speed of light ( the earth and star are stationary with respect to each other)
(a) Determine the time the trip from the earth to the star would appear to take from the perspective of both the person on earth and in the ship.
(b)Determine how far the ship will appear to have traveled during its trip from the perspective of both people. ( Hint- consider length contraction)
(c) Determine the apparent velocity of the ship from the perspective of both people.
Physics Modern Physics Level: University
AtomThis is another wavefuntion problem where the wave travel through three regions. The first region is before the barrier the second is the barrier and the third is after the barrier. Suppose that U ( sub-0)=0.500 eV and w=2.00 W is the width of the barrier. What fraction of the orginal wave is transmitted if the total energy of the electron is
(a) 0.800 eV
(b) 0.250 eV
(c) 0.100 eV
Explain all issues involved.
Physics Modern Physics Level: University
AtomAt a temperature of 20 degrees celius determine the probability that an electron can occupy a state 0.135 eV above the fermi energy.
Physics Modern Physics Level: University
AtomThis problem deals with the wave funtion and it traveling through a ( step - up) barrier of potential energy. The region before the barrier the region in the barrier and the region after the barrier. Explain how quantum mechanice can allow the wave to exist in all three regions but especially in the region of the potential of height U(sub-o) 0 x w. How is the wave in region 1 ( before barrier) connected to the wave in region 3 ( after barrier)? Explain in detail how to find the probablility ( analytically- that is as a fromula that shows the relations but that you do not solve all the way) that the wave is transmitted through the barrier. Is this allowed in classical physics? Why or why not.
Physics Modern Physics Level: University
Dual Nature of Matter and RadiationThe energy gap is 1.1 eV in room temperature silicon.
(a) What is the lowest energy photon that can excite an electron from the valence band into the conduction band? Why is it the lowest? Explain.
(b) What is the photons frequency? Wavelength?
Physics Modern Physics Level: University
Electron DensityIn a doped semiconductor the band gap is 0.078 eV. Compare the proportion of the charge carries in the semiconductor at room temperature and at 300 degrees celius.
