su11EIIIS - Exam III Solutions Part A. Multiple choice...

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Unformatted text preview: Exam III Solutions Part A. Multiple choice questions. Check the best answer. Each question carries a value of 4 points. 1. In a series circuit with an AC generator, a resistor and an inductor, the inductance is increased. Averaged over a cycle, the power input from the generator: Stays the same and the inductor consumes more of it. Is increased and the inductor consumes more of it. Stays the same and the inductor consumes none of it. √ Is decreased and the inductor consumes none of it. 2. Shown is a plot of reFectivity R vs angle of incidence θ 1 . The light is incident from a medium with refractive index n 1 on a medium with index n 2 . Which of the following is wrong? The light is polarized with E in the plane of incidence. [Brewster angle.] The indices obey n 1 > n 2 . {Total reFection.] √ The plot for E perpendicular to the plane of incidence differs from this one in that the angle at which R = is smaller. [In the other one there is no Brewster angle.] The angle at which R = is given by tan θ 1 = n 2 / n 1 . R θ 1 (radians) π / 2 Physics 54 Summer 2011 1 3. An e-m wave in vacuum of wavelength 3 μ m is polarized with its E-Feld in the z- direction and its B-Feld in the y-direction. Which of the following is NOT true? The wave moves in the negative x-direction. The frequency of the wave is 10 14 Hz. √ In a medium with n = 4/3 the frequency will be 0.75 × 10 14 Hz. [No change.] This wave is not visible to the human eye. [Take c = 3 × 10 8 m/s.] 4. A refracting telescope and a compound microscope both use two lenses of positive focal length. Which statement is NOT true about these instruments? The objective lens of the microscope has much shorter focal length than that of the telescope. √ In both instruments the objective lens makes an enlarged real image. [¡or the telescope this image is reduced.] ¡or both the angular magniFcation is inversely proportional to the focal length of the eyepiece....
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This note was uploaded on 10/19/2011 for the course PHYSICS 54L taught by Professor Thomas during the Summer '09 term at Duke.

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su11EIIIS - Exam III Solutions Part A. Multiple choice...

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