Calculate
(a) Calculate the shortest wavelength EMR that has high tansmission
through CdS. The energy gap in CdS is 2.25 eV.
(b) Is a photon with energy 2.26 eV transmitted or absorbed?
(c) Is a photon of energy 2.24 eV transmitted or absorbed?
(b) Photons of energy greater than 2.25 eV are absorbed, thus a photon of 2.26 eV is absorbed.
(c) A photon of energy 2.24 eV is transmitted because it cannot excite electrons from the valence band into the conduction band.
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When a switch is closed to complete a DC series RL circuit,
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A man stands on a scale in an elevator as shown here. The force of his weight when the elevator is still is Fg downward. Suppose the elevator's acceleration downward is 1/4 g. The weight of the man, Fs, is then:
a. 1/4 Fg. b. 1/2 Fg. c. 3/4 Fg. d. 3/2 Fg. e. 5/4 Fg.
The Earth is instantly replaced in its orbit by a speck of dust. Which statement best describes the subsequent orbital motion of that piece of dust?
A) The dust particle will move to a larger orbit and orbit the Sun in more than 1 year. B) The dust particle will continue in the same orbit as the Earth did, orbiting the Sun in 1 year. C) The dust particle will move to a smaller orbit and orbit the Sun in less than 1 year. D) The dust particle will spiral into the Sun. E) The dust particle will be ejected from the Solar System.