[开课学院]: 理工学院 [开课系所]: 综合班 [课程名称]: 普通物理(二) [老师名称]: 杨凯贤老师 [开课学期]: 972 [类型]: 97-2期末考 A. Choice Question(30%): 1. At a certain instant, a prioon is moving in the positive x direction(+x) through a magnetic field in the negative z direction(-z). What is the direction of the magnetic force exerted on the proton? (a) x (b) -x (c) y (d) -y (e) z (f) -z (g) The force is zro. 2. [Multi-choice] What creates a magnetic field? (a) a station objecct with electric charge (b) a moving object with electric charge (c) a stationary conductor carrying electric current (d) a difference electric potential (e) an elecrtic resistor 3. Rank the magnitudes of ∮B‧ds for the closed paths a through d in Figure 1 from least to greatest. (a) d<c<b<a (b) b<d<cca (c) b<a=c=d (d) a=b=c=d 4. What is the direction of the current in the resistor in Figure 2 at an instant immediately after the switch is thrown closed? (a) left (b) right (c) both left and right (d) zero 5. If the current in an inductor is doubled, by what factor is the stored energy multiplied? (a) 4 (b) 2 (c) 1 (d) 1/2 (e) 1/4 6. Consider the AC circuit in Figure 3. The frequency of the AC source is adjusted while it is voltage amplitude is held constant. When does the lightbulb glow the brightest? (a) at high frequency (b) at low frequency (c) the same in at all frequency (d) can not be determined B. Fill-in-the-Blanks(30%): 1. In an RLC AC circuit, what are the inductive reactance ΧL = _(1)_, and capacitive reactance ΧC = _(2)_. What is the reasonance frequency ω0 = _(3)_ of the AC source in the circuit at which the maximum rms current occurs? 2. The energy density μB = _(4)_ at a point where the magnetic field is B. 3. The uniform magnetic feld B = _(5)_ in a solenoid with length l , turns N and current I. 4. The time-dependent current I(t) = _(6)_ in an RL circuit with a battery of emf ε. C.Problems(60%): 1. consider a circular wire loop of radius a located in the yz plane and carryinga steady current I as shown in Figure 4. Calculate the magnetic fueld at an axial point P a distance x from the center of the loop. 2. The conducting bar illustrated in Figure 5moves on two frictionless, parallel rails in the presence of a uniform magnetic field direction into the page. The bar has mass m, and it is length is l. The bar is given an initial velocity vi to the right and is released at t = 0. Find the velocity of the bar as a function of time. 3. Consider the circuit in Figure 6, taking ε = 6.00V, L = 8.00mH, and R = 4.00Ω. (a) What is the inductive time constant of the circuit? (b) Calculate the current in the circuit 250μs after the switch is closed. (c) What is the value of the final steady-state current? (d) After what time interval does the current reach 80.0% of its maximum value? 附加连结:http://0rz.tw/9VQi8 http://0rz.tw/38MRP 考试时老师会讲解题目 听不懂可以问 考试可带电子辞典 p.s 照片很模糊 只有手机没相机 请多多包含 --

※ 发信站: 批踢踢实业坊(ptt.cc) ◆ From: 125.230.184.200 ※ 编辑: mint77320 来自: 125.230.184.200 (06/16 15:01)