1 Physics 1251 Practice Final 1 1) The figure shows an LR circuit with a switch and a 240-volt battery. At the instant the switch is closed the current in the circuit and the potential difference between points a and b, Vab, are a. 0 A, 0 V b. 0 A, 240 V c. 0 A, +240 V d. 0.024 A, 0 V e. 0.024 A, +240 V 2) The point P lies along the perpendicular bisector of the line connecting two long straight wires S and T perpendicular to the page. A set of directions A through H is shown next to the diagram. When the two equal currents in the wires are directed into the page, the direction of the magnetic field at P is closest to the direction of a. A b. B c. C d. D e. E f. none of the above 3) A bar magnet is dropped from above and falls through the loop of wire shown below. The north pole of the bar magnet points downward towards the page as it falls. Which statement is correct? a. The current in the loop always flows in a clockwise direction. b. The current in the loop always flows in a counterclockwise direction. c. The current in the loop flows first in a clockwise, then in a counterclockwise direction. d. The current in the loop flows first in a counterclockwise, then in a clockwise direction. e. No current flows in the loop because both ends of the magnet move through the loop. 4) Four electrons move from point A to point B in a uniform electric field as shown below. Rank the electrons in diagrams I through IV by the changes in potential from most positive to most negative when traveling from A to B. a. I = II = III = IV. b. II = III > I > IV. c. III > I = IV > II. d. II > I = IV > III. e. I > II = III > IV.2 5) 6) A magnetic field is directed out of the page. Two charged particles enter from the top and take the paths shown in the figure. Which statement is correct? a. Particle 1 has a positive charge and particle 2 has a negative charge. b. Both particles are positively charged. c. Both particles are negatively charged. d. Particle one has a negative charge and particle 2 has a positive charge. e. The direction of the paths depends on the magnitude of the velocity, not on the sign of the charge. 7) The circuit to the right contains 4 100-W light bulbs. The emf is 110 V. Which light bulb(s) is(are) brightest? a. A b. B c. C d. D e. C and D3 10a) 10b) What is the ratio of the amplitude of sound wave A to the amplitude of sound wave B? 11) 12) Produced with a Trial Version of PDF Annotator - www.PDFAnnotator.com4 13) If the electric field in an electromagnetic wave is given by: , where k and ω are positive constants, write down an expression for the magnetic field in the same electromagnetic wave. 14) 15) Laser light of wavelength 633 nm is incident on two 13.0 μm wide slits are separated by 91.0 μm, and the resulting interference pattern is projected on a screen 3.50 m away from the slits. Calculate: a) The distance on the screen between the 2nd order bright interference fringe and the 1st diffraction minimum (the edge of the central diffraction envelope). b) The total number of bright fringes that appear within the diffraction envelope. Produced with a Trial Version of PDF Annotator - www.PDFAnnotator.com5 16) A 0.687 μm thick layer of transparent liquid with index of refraction 1.47 lies between two glass microscope slides, each having an index of refraction of 1.60. When illuminated with white light from above and viewed from above, what wavelengths of visible light will not be visible due to destructive interference? 17) Light with a wavelength of 275 nm is found to eject electrons from a certain metal at speeds of up to 9.27x105 m/s. Calculate the work function Φ and the cutoff frequency for this metal. 18) An electron in the ground state of a 1.00 nm wide, 1-dimensional infinite potential well absorbs a photon and transitions to its 2nd excited state. Calculate the frequency of one of the photons that could be emitted as the electron returns to the ground state. 19) A hydrogen atom in its ground state absorbs an ultraviolet photon with a wavelength of 93.78 nm. What is the value of n for the final state of the hydrogen atom? 20) A neutral Magnesium atom contains 12 electrons. If a 13th electron is added to the atom, list one set of possible values for n, l, ml, and ms for this 13th electron. Produced with a Trial Version of PDF Annotator -
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