Giáo khoa vật lý 12 (Tiếng Anh)

MINITRY OF EDUCATION AND TRANNING PHYSICS 12 2000 Translated by VNNTU – Dec. 2001 Page 2 TABLE OF CONTENTS Part I. OSCILLATIONS AND WAVES 8 Chapter I – Mechanical Oscillations 8 §1. Periodic and simple harmonic motions. Oscillation of a mass-spring system. 8 1. Oscillations 8 2. Periodic motion 8 3. Mass-spring system. Simple harmonic motion 8 §2. Exploring a simple harmonic motion 10 Uniform circular motion and simple harmonic motion 10 2. Angular phase and angular frequency of a simple harmonic motion 11 3. Free motion 11 4. Velocity and acceleration in a simple harmonic motion 11 5. Oscillation of a simple pendulum 12 §3. Energy in a simple harmonic motion 13 1. Energy changes during oscillation 13 2. Conservation of mechanical energy during oscillation 14 §4. - §5. The combination of oscillations 15 1. Examples of the combination of oscillations 15 2. Phase-differences between oscillations 15 3. Vector-diagram method 16 4. The combination of two oscillations of same directions and frequencies 16 5. Amplitude and initial phase of the combinatorial oscillation 17 §6. - §7. Underdamped and forced oscillations 18 1. Underdamped oscillation 18 2. Forced oscillation 18 3. Resonance 19 4. Applying and surmounting resonant phenomenon 19 5. Self-oscillation 20 Summary of Chapter I 20 Chapter II – Mechanical wave. Acoustics 22 §8. Wave in mechanics 22 1. Natural mechanical waves 22 2. Oscillation phase transmission. Wavelength. 22 3. Period, frequency and velocity of waves 23 4. Amplitude and energy of waves 23 §9. - §10. Sound wave 24 Sound wave and the sensation of sound 24 2. Sound transmission. Speed of sound 25 3. Sound altitude 25 Timbre 25 5. Sound energy 26 6. Sound loudness 26 7. Sound source – Resonant box 27 §11. Wave interference 28 1. Interferential phenomenon 28 Translated by VNNTU – Dec. 2001 Page 3 2. Theory of interference 28 3. Standing wave 29 Summary of Chapter II 31 Chapter III – Electric oscillation, Alternating current 32 §12. Harmonic oscillation voltage. Alternating current 32 1. Harmonic oscillation voltage 32 2. Alternating current 32 3. Root mean square (rms) value of intensity and voltage 33 §13. - §14. Alternating current in a circuit containing only resistance, inductance or capacitance 34 1. Relation between current and voltage 34 2. Ohm’s law for an AC circuit containing only resistance 34 1. Effect of capacitors to the alternating current 34 2. Relation between current and voltage 35 3. Ohm’s law for an AC circuit containing only capacitance 35 1. Effects of an inductor to the alternating current 36 2. Relation between current and voltage 36 3. Ohm’s Law for an AC circuit with inductors 36 §15. Alternating current in an RLC circuit 37 Electric current and voltage in an RLC circuit 37 Relation between current and voltage in an RLC circuit 38 3. Ohm’s Law for an RLC circuit 38 4. Resonance in an RLC circuit 39 §16. Power of the alternating current 39 1. Power of the alternating current 39 2. Significance of the power coefficient 40 §17. Problems on AC circuits 41 Problem 1 41 Problem 2 41 §18. Single-phase AC generator 42 1. Operational principle of single-phase AC generators 42 2. Structure of an AC generator 42 §19. Three-phase alternating current 43 1. Operational principle of three-phase AC power generators 43 2. WYE connection 44 3. Delta connection 45 §20. Asynchronous three-phase motors 45 Operational principle of asynchronous three-phase motors 45 Rotating magnetic field of three-phase current 46 3. Structure of an asynchronous three-phase motor 46 §21. Transformers. Electricity transmission 47 1. Operational principle and structure of transformers 47 2. Transformation of current and voltage via transformer 47 3. Transmission of power 48 §22. Generation of direct current 49 1. Benefits of direct current 49 Half-cycle rectifying method 49 Translated by VNNTU – Dec. 2001 Page 4 3. Two half-cycle rectifying method 49 4. Operational principle of DC power generators 50 Summary of Chapter III 50 Chapter IV – Electromagnetic oscillation. Electromagnetic wave 52 §23. Oscillation circuits. Electromagnetic oscillation 52 1. Fluctuation of charges in an oscillation circuit 52 2. Electromagnetic oscillation in an oscillation circuit 53 §24. Alternating current, high-frequency electromagnetic oscillation, and mechanical oscillation 54 1. Electric oscillation in an alternating current 54 2. High-frequency electromagnetic oscillation 54 3. Electromagnetic oscillation and mechanical oscillation 54 §25. Electromagnetic field 57 1. Fluctuated electric field and fluctuated magnetic field 57 2. Electromagnetic field 57 3. Transmission of electromagnetic interaction 57 §26. Electromagnetic waves 58 1. Electromagnetic waves 58 2. Properties of electromagnetic waves 58 3. Electromagnetic waves and wireless communication 58 §27. Transmitting and receiving electromagnetic waves 59 Periodic-oscillation transmitters using transistors 59 2. Open oscillation circuit. Antenna 60 Principles of transmitting and receiving electromagnetic waves 60 §28. - §29. A glance at radio transmitters and receivers 61 1. Principle of oscillation amplification 61 2. Principle of amplitude modulation 62 3. Operational principle of radio transmitters 62 4. Operational principle of radio receivers 63 Summary of Chapter IV 64 Part II. OPTICS 66 Chapter V – Light reflection and refraction 66 §30. Light transmission. Light reflection. Plane mirror 66 1. Light propagation 66 2. Light reflection 67 3. Plane mirror 67 §31. Concave spherical mirrors 68 Definitions 68 2. Reflection of a light in a concave spherical mirror 69 3. Formation of images by concave spherical mirror 69 4. Main focal point. Focal length 70 5. Method to draw an object’s image obtaining from a concave spherical mirror 70 §32. Convex spherical mirrors. Convex spherical mirror equations. Applications of convex spherical mirrors 72 1. Convex spherical mirror 72 2. Convex spherical mirror equations 72 3. Applications of convex spherical mirrors 74 Translated by VNNTU – Dec. 2001 Page 5 §33. Light refraction 75 Light refraction phenomenon 75 2. The law of light refraction 75 3. Index of refraction (refractive index) 76 §34. Total internal reflection 77 Total internal reflection 77 2. Conditions to achieve total internal reflection 78 3. Critical angle 78 4. Applications of total internal reflection 79 §35. Prism 80 1. Definition 80 2. Path of a monochromatic ray through a prism. Angle of deviation 80 3. Prism equations 80 4. Minimum deviation angle 80 §36. Thin lenses 82 1. Definition 82 2. Main focal point. Optical center. Focal length 82 3. Supplemental focal points. Focal plane 83 4. Lens power 84 §37. Image of an object through lenses. Lenses equations 85 1. Observing an object’s image through a lens 85 2. Method to draw an object’s image through a lens 85 3. Lens equation 86 4. Lateral magnification 87 The human eye and optical instruments 91 §38. Camera and the human eye 91 1. Camera 91 2. The human eye 91 §39. Eye’s defects and correcting methods 94 1. Near-sightedness (myopia) 94 Farsightedness (hyperopia) 95 1.State the characteristics of near-sighted eye and the correcting method. 95 §40. Magnifying glass 95 1. Definition 95 2. Near point and infinite point 96 3. Angular magnification 96 §41. Microscope and telescope 98 1. Microscope 98 2. Telescope 99 Chapter VII – The wave-nature of light 103 §42. Light dispersion phenomenon 103 1. Experiment on light dispersion phenomenon 103 2. Experiment on monochromatic light 103 3. Synthesizing white light 104 4. Dependence of the index of refraction of a transparent medium on the color of the light 104 §43. Light interference phenomenon 105 Translated by VNNTU – Dec. 2001 Page 6 1. Young's experiment on light interference phenomenon 105 2. Explanation of the phenomenon 105 3. Conclusion 106 1. Describe the experiment on the interference of light? 106 §44. Measuring the wavelength of the light. The wavelength and the color of the light 106 1. Interference fringe distance 106 2. The wavelength and the color of the light 108 §45. Spectrometer. Continuous spectrum 108 1. Relation between the index of refraction of a medium and the wavelength of the light 108 2. Spectrometer 109 3. Continuous spectrums: 109 §46. Line spectrum 110 1. Emission line spectrum 110 2. Absorption line spectrum 111 3. The spectroscopic analysis approach and its advantages 112 §47. Infrared and ultraviolet rays 112 1. Experiments to discover infrared and ultraviolet rays 112 2. The infrared ray 113 3. The ultraviolet ray 113 §48. X-rays 114 1. X-ray tube 114 2. The nature of X-rays 114 3. Properties and uses of X-rays 114 4. Electromagnetic waves scale 115 Chapter VIII – Light quantum 118 §49. The photoelectric effect 118 1. Hertz’s experiment 118 The experiment with a photocell 118 §50. The quantum hypothesis and photoelectric laws 120 1. Photoelectric laws 120 2. The quantum hypothesis 120 3. Explaining photoelectric laws by using the quantum hypothesis 121 4. Wave-particle duality of the light 122 §51. Light dependant resistor and photoelectric battery 123 1. The photoconduction phenomenon 123 2. Light dependant resistor (LDR) 123 3. The photoelectric battery 124 §52. Optical phenomena relating to the quantum property of the light 125 1. The luminescence 125 2. Photochemical reactions 125 §53. Application of the quantum hypothesis to hydrogen atom 126 1. The Bohr model of the atom 126 2. Using the Bohr model to explain hydrogenous line spectrum 127 Summary of Chapter VIII 128 Part III. NUCLEAR PHYSICS 130 Chapter IX – Basic knowledge on the atomic nucleus 130 Translated by VNNTU – Dec. 2001 Page 7 §54. Structure of the nucleus. The unit for atomic 130 1. Structure of the nucleus 130 2. Nuclear forces 130 3. Isotopes 130 4. The unified atomic mass unit 131 §55. Radioactivity 132 Radioactivity 132 2. The radioactive decay law 133 §56. Nuclear reactions 134 1. Nuclear reactions 134 2. Conservation laws in nuclear reactions 134 3. Application of conservative laws to radioactivity. Transmutation rules 135 §57. Artificial nuclear reactions. Applications of isotopes 136 1. Artificial nuclear reactions 136 2. Particle accelerators 136 §58. Einstein’s relation between mass and energy 138 1. Einstein’s axioms 138 §59. THE LOSS OF MASS. NUCLEAR ENERGY 140 1. The loss of mass and binding energy 140 Exothermic and endothermic nuclear reactions 140 3. Two exothermic nuclear reactions 141 §60. Nuclear fission. Nuclear reaction plants 142 1. Chain nuclear reactions 142 Nuclear reaction plants 143 §61. THERMONUCLEAR REACTION 144 Supplemental reading: Primary Particles 145 1. Properties of the primary particles: 145 2. Antiparticles. Antimatter. 146 3. Fundamental interactions. Classification of primary particles. 146 4. Quarks 147 SUMMARY of chapter IX 147 Part IV. PRACTICAL EXPERIMENTAL EXERCISES 150 Experimental exercise 1 – Clarification of the law on the simple pendulum’s oscillation. Determination of the gravity acceleration 150 Experimental exercise 2 – Determination of Sound wavelengths and frequencies 152 Experimental exercise 3 – The alternating current circuit with R, L, C 154 Experimental exercise 4 – The refraction index of glass 156 Experimental exercise 5 – Observation of light dispersion and interference phenomena 158 COMBINED EXPERIMENTAL EXERCISES 160 Experimental exercise A – Determination of Capacitance and inductance (2 sections) 160 Experimental exercise B – Characteristics and applications of transistors (2 sections) 163 Experimental exercise C – Determination of focal length of lenses (2 sections) 166 Translated by VNNTU – Dec. 2001 Page 8 Part I. OSCILLATIONS AND WAVES Chapter I – MECHANICAL OSCILLA TIONS §1. P ERIODIC AND SIMPLE HARMONIC MOTIONS . O SCILLATION OF A MASS - SPRING SYSTEM . 1. Oscillations Flower stirs in the branch as the wind breezes. Pendulum of the clock swings to the left and right. On the rippled lake, a small piece of wood bobs and rolls. The string of the guitar vibrates when it is played. In the examples above, things move in a small space, not too far away from a certain equilibrium position. The movement likes that is called the oscillation . An oscillation, or vibration, is a limited motion on a space, repeating back and forth many times around an equilibrium position. That position often is where thing is at rest (does not move): when there is no wind, a clock does not work, a smooth lake, non vibrating guitar’s strings. 2. Periodic motion Observing the oscillation of a pendulum of the clock, after a certain period of time of 0.5s, it passes through a lowest position from the left to the right. The oscillation like that is called the periodic oscillation . Periodic oscillation is the oscillation whose state is repeated as it was after a constant period of time. The smallest period of time of T after that states of oscillation are repeated as they were is called the period of periodic oscillation. The quantity f = T 1 showing the number of oscillations (i.e. how many times a state of oscillation is repeated as it were) per unit of time is called the frequency . Frequency is usually specified in hertz (Hz). In the example above, the period of the pendulum is T = 0.5s so its frequency is f = 5.0 1 = 2Hz, it means that the pendulum carries out 2 oscillations in a second. The vibration of the guitar’s strings do not permanently maintained. It is damped then ended. But if it is observed in a very small period of time, it is approximately a harmonic oscillation . 3. Mass-spring system. Simple harmonic motion Considering a mass-spring system consisted of a small ball of m kg attached rigidly to a spring of negligible mass, put in the horizontal plane as shown (figure 1.1a). There is a small hole through the ball so it can be translated along a fixed rod in the same plane. We choose a datum axis that coincides with the rod, is directed from the left to the right, and the origin O is the equilibrium position of the ball (position where the ball is at rest). A ball is deflected to the right by a force F then released (figure 1.1b; the spring is not shown). It is observed that the ball moves toward Translated by VNNTU – Dec. 2001 Page 9 the point O, passes through O. This translation is repeated many times, i.e. the ball oscillates around the equilibrium position O. This phenomenon is analyzed as following: when the ball is pulled to an ordinate x, forces exert into it consist of the pulling force F’ , the elastic force F of the spring, the gravity force and the reacting force of the rod to the ball (these two forces are not shown in the figure). The gravity and reacting force are in the vertical plane, equal to each other and opposite in the direction so they have no affect on the horizontal translation of the ball. At the time the ball is released, there is only an elastic force exert on it. Within the limitation of elasticity of the spring, the force F is always proportional with the displacement x of the ball from the equilibrium position (is also the deflection of the spring), and directs toward the point O. Since F is along the coordinate axis, it can be written as: F = - kx (1-1) Here k is the spring constant (stiffness) of the spring, and the minus sign indicates that the force F is acting in opposite direction compared with the deflection x of the ball. According to Newton’s second law, it can be written as F = ma, or ma = - kx. Thus a = x m k − . It is known that a velocity and acceleration are defined by v = t x ∆ ∆ and a = t v ∆ ∆ . If the motion is investigated in a very small period of time ∆t, then t x ∆ ∆ becomes a derivative of x with respect to time variable, v = x ! ; similarly, t v ∆ ∆ becomes a derivative of x respecting to time t, a = v ! , i.e. a second order derivative of x with respect to time variable: a = x !! . Therefore we have x !! = x m k − (1-2) Let ω = m k then x !! + ω 2 x = 0 (1-2a) It can be proved having a solution of x = Asin(ωt+ϕ) (1-3) where A and ϕ are constants and ω = m k . Really , taking derivative of the displacement x (1-3) with respect to the time variable we have the velocity of the ball : v = x ! = ω Acos( ω t + ϕ ) (1-4) Taking derivative of the velocity v (1-4) with respect to the time, we get the acceleration of the ball: a = x !! = - ω 2 Asin( ω t + ϕ ) (1-5) Replacing the value of x into (1-5) we get: x !! = - ω 2 x (1-6) (1-6) has the same format as (1-2a), it shows that (1-3) is the solution of (1-2a), in another way, the equation of the oscillated ball is x = Asin( ω t + ϕ ). Since sine function is a periodic function, it is said that the oscillation of the ball (i.e. the oscillation of the mass-spring system) is a simple harmonic motion (SHM). Note that a cosine expression can be transformed to a sine expression such a way that: Acos(ωt+ϕ) = Asin(ωt+ϕ+π/2) Therefore, it can be defined that a SHM is an oscillation that can be described by a sinusoidal (or cosinusoidal) function, where A, ω, ϕ are constants. In the equation (1-3), x is the displacement of the oscillation, showings precisely the deflection of the ball from the equilibrium position. A is the amplitude of the oscillation. It is the maximum value of Translated by VNNTU – Dec. 2001 Page 10 displacement, occurred when sin(ωt+ϕ) has the maximum value of 1. The meanings of ω, ϕ and ωt+ϕ will be clarified at §2. It is known that sine function is a periodic function with the period of 2π. Thus, it can be written as x = Asin(ωt +ϕ) = Asin(ωt +ϕ +2π), or x = Asin[ω(t + 2π ω ) + ϕ] It means that the displacement of the ball at time (t + ω π 2 ) have the same value at time t. The period of time T = ω π 2 is called the cycle of the SHM. The reciprocal of T, f = T 1 = π ω 2 is called the frequency of the SHM. Particularly, for the mass-spring system, we have T = ω π 2 = 2π k m (1-4) Now the system is taken out from the rod and hung up vertically (figure 1.1c). If the ball is pulled down then released, it will oscillate in the vertical direction. That is also a mass-spring system. Everything have been said about a horizontally oscillated spring system can be applied to a vertically oscillated spring system as well. In this case, the equilibrium position is no longer the point O that corresponds with the time the spring was not deflected, but is a point O’ that corresponds to the time the spring was deflected due to the gravity of the ball. Questions 1. Make statement about the definitions of oscillation, periodic oscillation and harmonic oscillation? 2. Differentiate between periodic and general oscillation, between periodic and harmonic oscillation? 3. Make statement about the definitions of time constant, frequency, displacement, amplitude of harmonic oscillation? 4. Give more example about oscillation and harmonic oscillation? §2. E XPLORING A SIMPLE HARMONIC MOTION 1. Uniform circular motion and simple harmonic motion Let consider a point M moves in a circle of central point O and radius A (figure 1.2). The angular velocity of point M is ω (measured in rad/s). A point C in the circle is chosen to be an origin. At the initial time t = 0, the position of the moving point is M 0 , is specified by an angle of ϕ. At an arbitrary time, the position of the moving point is M t specified by an angle of (ωt + ϕ). We project the path of point M onto an axis x’x pass through point O and perpendicular to OC. At time t, the projection of point M onto x’x axis is point P which has the ordinate of x = OP. Since OP is the projection of OM t onto the x’x axis so we have: x = OM t sin(ωt +ϕ) x = Asin(ωt +ϕ) (1.8) (1.8) has the same format as (1.3) so we can conclude that the motion of point P on the x’x axis is a SHM. In the other wa y, a simple harmonic oscillation can be considered as the projection of an uniform circular motion onto any straight line in the same plane. [...]... equation I0 = U0 , if the two sides are divided by R 2: I= U R (3 -12) where I and U are rms values of current and voltage respectively Formula (3 -12) shows Ohm’s law for an AC circuit containing only resistance, in the same form as for a DC circuit Note that (3-10) shows the relationship between i and u which is valueless in the real life, while (3 -12) shows the relationship between the rms values I and U... Translated by VNNTU – Dec 2001 Page 33 4 Write the oscillation equations of alternating voltage in the case that the rms voltage and the frequency are: a) 220 V, 50 Hz; b) 127 V, 60 Hz Hints: 4 a) u = 311sin100πt (V); b) u = 180sin120πt (V) §13 - §14 ALTERNATING CURRENT IN A CIRCUIT CONTAINING ONLY RESISTANCE, INDUCTANCE OR CAPACITANCE Normally, an AC circuit in a household equipment contains both resistance,... proportional with the magnitude of amplitude vector A It is necessary to evaluate A and ϕ in (1-24) For triangle OMM2 in figure 1.7, we have: " OM 2 = OM 2 + M 2 M 2 − 2OM 2 M 2 M cos OM 2 M , or 2 " A2 = A12 + A12 – 2A1A2cos OM 2 M " " Since OM 2 M and M 2 OM are supplementary angles thus: " " cos OM 2 M = - cos M 2 OM = - cos(ϕ2 - ϕ1) (1-25) From figure1.7 we can deduce that tgϕ = MP ' OP A1 sin ϕ1 + A 2... physiological characteristics of human ears, the threshold of hearing changes according to sound frequencies With the sound frequencies in the range of 1000 – 5000Hz, the threshold of hearing is about 10 -12 W/m2 With the frequency of 50Hz, the threshold of hearing is 105 times bigger Thus, a sound wave of frequency 1000Hz and of intensity 10-7 W/m2 is considered ‘very loud’ to the human ear, while another... that should be noted: Translated by VNNTU – Dec 2001 Page 26 The threshold of hearing 0dB Noises in a room 30dB Noises in a busy supermarket 60dB Noises on the street 90dB The sound of a big lightning 120 dB The threshold of hurting 130dB Sounds with high intensity make stresses and tiredness to human Living or working long time in a place of high sound-intensity reduces the sharpness of the ears, and... wavelength λ and to determine the speed of wave v when the wavelength λ and the frequency f are all known Translated by VNNTU – Dec 2001 Page 31 Chapter III – ELECTRIC OSCILLATIO N, ALTERNATING CURRENT 12 HARMONIC OSCILLATION VOLTAGE ALTERNATING CURRENT 1 Harmonic oscillation voltage Let a metal loop of area S and turn N uniformly rotate around its symmetrical axis xx’ in a uniform magnetic field B whose... applied the analysis process in §1 and §2 as well then it can be concluded that the motion of a single pendulum is a harmonic oscillation with angular frequency ω = g l Translated by VNNTU – Dec 2001 Page 12 The time constant of the pendulum is: T= 2π g = 2π l ω (1-15) For small oscillation, i.e with α ≤10o, the cycle of a simple pendulum is not dependent on the oscillation amplitude All the discussion... which α is small enough to have " the arc OP coincide with the chord OP and sinα can be approximated as α (in radian) If α ≤10o then the error is not greater than 6/1000 Thus we have: sinα ≈ α = s l (1 -12) Now, the ball is released and it swings itself The force acting on the ball include of the gravity Ft = mg, the tend force T of the string The force Ft is resolved into 2 components: F’ in the direction . photoelectric laws 120 1. Photoelectric laws 120 2. The quantum hypothesis 120 3. Explaining photoelectric laws by using the quantum hypothesis 121 4. Wave-particle duality of the light 122 §51. Light. battery 123 1. The photoconduction phenomenon 123 2. Light dependant resistor (LDR) 123 3. The photoelectric battery 124 §52. Optical phenomena relating to the quantum property of the light 125 1 the light 125 1. The luminescence 125 2. Photochemical reactions 125 §53. Application of the quantum hypothesis to hydrogen atom 126 1. The Bohr model of the atom 126 2. Using the Bohr model to