课程名称︰普通物理学甲下 课程性质︰化学系必带,地质系选修 课程教师︰蔡政达 开课学院：理学院 开课系所︰物理系 考试日期（年月日）︰2010.06.22 考试时限（分钟）：120 mins 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : 1. A parallel-plate capacitor with circular plates of radius R is being charged as in Fig A (a)Derive an expression for the magnetic field at radius r for the case r≦R (8 points) (b)Evaluate the field magnitude B for r=R/5=10 mm and dE/dt=1.00*10^12V/ms (4 points) (c)Derive an expression for the induced magnetic field for the case R≦r (8 points) │+-│ ├→┤ │+-│ ├→┤ i│+-│ i →├→┤→ │+-│ ├→┤ │+-│ ├→┤ │+-│ ├→┤ │+ │ _____ ╱ ╲ ╱ B ╲ ∕ → ﹨ ∕ ﹨ ∣ ∣ ∣ B↑ ↓B ∣ ﹨ ∕ ﹨ ← ∕ ╲ B ╱ ╲______╱ 2. A silt of width a is illuminated by white light. (a)For what value of a will the first minimum for red light of wavelength λ=600 nm appear at θ=30 degrees? (10 points) (b)What is the wavelength λ' of the light whose first side different maximum is 30 degrees, thus coinciding with the first minimum for the red light? (10 degrees) 3. An eraser of height 1.0 cm is placed 10.0 cm in front of a two-lens system. Lens 1 (nearer the eraser) has focus length f1=-15cm, lens 2 has f2=12cm, and the lens separation is d=12cm. For the image produced by lens 2, what are (a)the image distance i2 (including sign),(5 points) (b)the image height,(5 points) (c)the image type (real or virtual),(5 points) and (d)the image orientation (inverted relative to the eraser or not inverted)? (5 points) 4. In Fig B, two isotropic point sources of light (S1 and S2) are separated by distance 3.0 um along a y axis and emit in phase at wavelength 1200 nm and the same amplitude. A light detrctor is located at going P at coordinate Xp on x axis (1)What is the greatest value of Xp at which the detected light is minimum due to destructive interference?(10 points) (2)When P is very far away (x~∞), what are the phase different (in terms of wavelengths) between waves arriving S1 and S2?(5 points),and the type of interference they produce (approximately fully constructive or destructive?) (5 points) y │ S1│ P ────●─────●──x │ │ │ ●S2 │ │ 5 In a photoelectric experiment using a sodium surface, you find a stopping potential of 1.85 V for a wavelength of 300 nm and a stopping potential of 0.820 V for a wavelength of 400 nm .From these data find (a)a value for Planck constant (7 points) (b)the work function Φ for sodium (7 points) (c)the cutoff wavelength λ0 for sodium (6 points) --

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