Q- Kr-85 is a radioactive isotope that is used in measuring paper thickness. It decays by emission with a half-life of 10.8 years
(a) Write down the decay equation showing the daughter isotope and decay products of this process.
(b) A Kr-85 source had activity 30 mCi when new. Estimate its activit…
Q- (a) What are the energies of the first three energy levels of an electron confined in a one-dimensional box of length 0.75 nm?
(b) How much energy must the electron lose to move from the n = 3 energy level to the n = 1 energy level?
(c) Suppose that an electron can move from the n = 3 level to …
Q- The first three energy levels of the fictitious element X are E1 = -3.8 eV, E2 = -1.7 eV, and E3 = -1.2 eV. Element X has one electron in the ground state.
(a) What is the ionization energy of element X?
(b) Calculate the (i) shortest and (ii) next-shortest wavelengths observed in the absorpti…
Q- The measurements of a photoelectric-effect experiment are graphed in in Figure, in which the intervals along the horizontal and vertical axes are respectively given by 5.9*1014 Hz and 2.50 V, respectively.
(a) What is the work function of the cathode?
(b) What experimental value of Planck's con…
Q- A 150 W light bulb emits about 8 W of visible light. (The other 142 W are emitted as infrared radiation or lost as heat to the surroundings.) The average wavelength of the visible light is about 510 nm, so make the simplifying assumption that all the visible light has this wavelength.
(a) What i…
Q- Electrons with a speed of 2.5 *106 m/s pass through a double-slit apparatus. Interference fringes are detected with a fringe spacing of 1.6 mm.
(a) What will the fringe spacing be if the electrons are replaced by neutrons with the same speed?
(b) What speed must neutrons have to produce interfe…
Q- An electron in Chromium (Z=24) moves from the n=2 to the n=1 state without emitting a photon. Instead, the excess energy is transmitted to an outer electron (n=4 state), which is emitted. This is called an Auger Electron. Using ionization considerations, calculate the kinetic energy of the Auger …
Q- Light from a laser hits the surface of cesium, with minimum photon energy of 2.5 eV being required to remove photons. When the surface of cesium is illuminated with this light photo-electrons are emitted with a max kinetic energy of 0.75 eV. What would be the energy of the photons comprising the …
Q- The sun radiates electromagnetic energy at a constant rate of 3.92*1026 W.
(a) What is the change in the sun’s mass during each second due to radiating energy?
(b) The mass of the sum is 1.99*1030 kg. What fraction of the sun’s mass is lost during a human lifetime of 75 years?
Comments