课程名称︰普通物理学下 课程性质︰必修 课程教师︰陈智泓 开课学院：理学院 开课系所︰物理系 考试日期（年月日）︰103/06/19 考试时限（分钟）：2小时 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : 1.(10%)Two wires, parallel to a z-axis and a distanc 4r apart, carry equal currents i in opposite directions, as shown in the fig.1. A circular cylinder of radius r and length L has its axis on the z-axis onthe z-axis, midway between the wires. Use Gauss'Law for magnetism to derive an expression for the net outward magnetic flux through the half of the cylinder surface above the x-axis. write your answer in terms of the variables given and μ0. 2.In the fig. 2, a capacitor with circular plates of radius R is connected to a source of emf E=Vsin(wt). The maxium value of the displacement current is Id. Neglect fringing of the electric field at the edges of plates.(a)(5% What is the maxium value of the current i in the circuit? (b)(5%) What is the separation d between of dΦE/dt, where dΦE is the flux in the region between the palces? (c) (5%) what is the separation d between the plates. Find the maxium value (in time) of the magnetic field as a function of radial distance r from the center of the plates, for (d)(5%)r≧R and (e)(5%)r≦R. Given your answer in terms of R,V w,Id,μ0,E0. 3.(是非题) __ Consider a star which is 6 light year away. Aphoton from the star takes 6 years to reach the earth in our frame. However, it takes zero second from that photon's point of view. 4.(是非题) __ Einstein is the first person who derives that the length along the moving direction of an object becomes shorter than it is at rest. 5.(是非题) __ An object weights more when it is moving than a rest. 6.A rocket ship leaves eath at a speed 3/5c. When a clock pn the rocket says 1 hour has elaosed, the rocket sends a light signal back to earth. (a)(5%) According to earth clocks, when was the sighnal sent? (b)(5%) According to earth clocks, how long after the rocket left did the signs arrive back on the earth? (c)(5%) According to the rocket observer, how long after the rocket left the signal arrive back on earth? 7.Sophie and her twin brother are separated 500 km away. When her brother was hit by a hammer, she cries at the same time. A scientist observed both events (brother's accident and Sophie's cry) from an airplane traveling at 12/13c to right(Sophie was on right), where c is the speed of light. (4%) Which event occurred first, according to the scientist? (6%) How much earier was it, in seconds? 8.(25%) The Compton scattering is a scattering process between a photon and an electron is deflected by an angle θ and the electron is deflected by an angle ψ. The energy of photon is quantized by E0=hυ, where h is the Planck constant and theυis the frequency. Show that the wavelength of the photon λafter scatted satisfies the relation λ=λ0+(h/mc)(1-cosθ) where c is the speed of light. --

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