課程名稱︰普通物理學甲下 課程性質︰物理系必修 課程教師︰張寶棣 開課學院：理學院 開課系所︰物理系 考試日期（年月日）︰101/6/21 考試時限（分鐘）：160 是否需發放獎勵金：是 （如未明確表示，則不予發放） 試題 : 1. Please answer the following questions. ●what is circular polarized? What is the minimum reduction in the intensity when two polarizers are used to rotate the direction of polarization of polarization for linearly polarized light by 90 degrees? (5%) ●Explain how a permanent bar of magnet attract an unmagnetized iron needle. What is hysteresis? (5%) ●What is wavelet? Please use Huygens's priciple to describe refraction. (5%) 2.A conducting rod of length l=35.0cm is free to slide on two parallel conducting bars as shown in Fig.1. Two resistors R1=2.00Ω and R2=5.00Ω are connected across the ends of the Bars to form a loop. A constant magnetic field B=2.5T is directed perpendicular into teh paper. An external agent pulls the rod to the left with a constant speed of v=8.00m/s. Find (a) the current in both resistors, (b) the total power delivered to the resistance of the circuit, and (c) the magnitude of the applied force that is needed to move the rod with this constant velocity. ┌─────┬──┐ │x x x x x │x x│ R1 § v <─ │x x§R2 § x x x x │x x§ │x x x x x │x x│ └─────┴──┘ Fig.1 3.In Fig.2, the swirch is closed for t<0, and steady-state conditions are established.The switch is opened at t=0. (a) Find the initial voltage ε across L just after t=0. Which end of the coil is at the higher potential: a or b? (b) Draw current in R1 and R2 as a function of time, treating the steady-state direction as positive. Show value before and after t=0. (c) How long after t=0 does the current in R2 have the value 2.00mA? ┌─┬─R1┐ │ │ │ R1=2kΩ R2=6kΩ │ / S │ │ │ § _ R2 _ §←L=0.4H __ ←是電池 V=18.0V │ __ │ └─┴──┘ Fig.2 4.In the parallel circuit shown in Fig.3, Vmax=110V. (a) What is the impedance of each branch? (b) For each branch, what is the current amplitude and its phase relative to the applied voltage? (c) Give the current phasor diagram, and use it to find the total current and its phase relative to the applied voltage.(15%) ┌──┬──┐ │ R1 §←XL=30Ω R1=10Ω R2=40Ω │ │ │ ~~ ─ │ │ -- R2 ─ │ │ │ __ ←電容 Xc=10Ω ~~是交流電 └──┴──┘ 5.The reflected light from an oil film floating on water show destructive interference for light of wavelength 550nm, 610nm and 685nm incident along the normal. The index of reflection of the oil is n=1.4. What is the oil minimun possible thickness? (10%) 6.Light of the wavelength 690nm from a ruby laser impinges on two slits 1.1mm apart. Each slit is 0.2mm wide. Find the intensity ratio I/I0 on a screen 3.0 m away at the following distances from the central maximun:0.05mm, 0.5mm, 1.5 mm, and 3.0mm. (10%) 7.Two parallel wires, each of radius R are separated by distance d>>R. The wire carry equal currents in opposite directions. Wire of this type is used frequently to connect your TV to its aerial. (a) Find teh magnetic flux of the current in the rectangular area between the edges of the two wires(assume that the rectangular length is L) (5%) (b) find the inductance per unit length of the wire. (5%) 8.The total electromagnetic power emitted by the sun is 3.8*10^26 W. What is the radiation pressure exerted on a total reflecting surface a distance r=1.0*10^10m from the sun? Calculate the magnitude at this point. (10%) --

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