Presentation on theme: "Review. The Wave Nature of Light Important: When a light wave travels from one medium to another, its frequency does not change, but its wavelength does."— Presentation transcript:
Important: When a light wave travels from one medium to another, its frequency does not change, but its wavelength does.
1.Why we do not notice any dispersion when light passes through a windowpane?
1.What does the dispersion of light tell us about the speeds of various colors of light in a material? 2.Will the converging lens focus blue light or red light at a closer distance to the lens? Explain.
1.Would yellow light or green light produce the wider two- slit interference pattern? 2.If light and sound are both wave phenomena, why can we hear sounds around a corner but cannot see around a corner? 3.Red light is used to form a two-slit interference pattern on a screen. As the two slits are moved farther apart, does the separation of the bright bands on the screen decrease, increase, or remain the same?
1.Why can’t an ordinary microscope using visible light be used to observe individual molecules? 2.Is it better to use red light or blue light to minimize diffraction effects while photographing tiny objects through a microscope? Why? 3.Why are the diffraction effects of your eyes more important during the day than at night?
A blackbody is a body that would absorb all the radiation falling on it.
Planck’s Quantum Hypothesis Planck’s assumption suggests that the energy of any molecular vibration could be only some whole number multiple of hf:
1.If all objects emit radiation, why don’t we see most of them in the dark? 2.Rutherford’s model provided an explanation for the emission of light from atoms. What was this mechanism and why was it unsatisfactory? 3.Suppose you were a nineteenth-century scientist who had just discovered a new phenomenon known as Zeta rays. What experiment could you perform to define if Zeta rays are charged particles or e/m waves? Could this experiment distinguish between neutral particles and an e/m wave?
1.An increase in intensity of the light beam means more photons are incident, so more electrons will be ejected, but max KE in not changed. 2.If the frequency of the light is increased, the max KE increases linearly. 3.If the frequency f is less than the “cutoff’ frequency f 0, no electrons will be ejected at all, no matter how big is the intensity.
1.If a metal surface is illuminated by light at a single frequency, why don’t all the photoelectrons have the same kinetic energy when they leave the metal’s surface? 2.What property of the emitted electrons depends on the intensity of incident light? 3.What property of the emitted photoelectrons depends on the frequency of incident light?
n – principal quantum number, positive integer; l – orbital quantum number, is related to the magnitude of the angular momentum of the electron; at given n can take integer values from 0 to (n-1); m l – magnetic quantum number, is related to the direction of the electron’s angular momentum, and it can take an integer values from –l to +l.
1.How many electrons have the quantum numbers n=5 and l=1? 2.How many electrons can have the quantum numbers n=5 and l=4? 3.Why do some minerals glow when they are illuminated with ultraviolet light?
1.Which of the three types of radiation will interact with electric field? 2.Why do beta rays and alpha rays deflect in opposite directions when moving through a magnetic field?
1.What happens to the charge of the nucleus when it decays via beta plus decay? 2.What happens to the charge of the nucleus when it decays via electron capture? 3.What changes in the numbers of neutrons and protons occur when a nucleus is bombarded with a deuteron (containing one neutron and one proton) and an alpha particle is emitted?
1.You place a chunk of radioactive material on a scale and find that it has a mass of 4 kilogram. The half-life of the material is 10 days. What will the scale read after 10 days? 2.A radioactive material has a half-life of 50 days. How long would you have to watch a particular nucleus before would see it decay?