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大学物理-电磁学（英文授课）IntroductionElectromagnetism is a field of physics that concerns itself with the study of electromagnetic forces and fields. It is a branch of physics that focuses on the interaction between electrically charged particles, including charged particles at rest and moving charges. This course is designed to help students understand the basic principles of electromagnetism, including electric and magnetic fields, electromagnetic radiation, and electromagnetic waves.Electric FieldsElectric fields are created by electric charges, which are either positive or negative. The electric field is said to be the space surrounding a charged particle. If another charged particle is placed in the electric field, it will experience a force. The direction of the force depends on the charge of the particle and the direction of the electric field.Magnetic FieldsMagnetic fields are created by moving charges. A magnetic field is said to be the space surrounding a magnetic object. If a charged particle is placed in a magnetic field, it will move in a circular path. The direction of the circular path depends on the charge of the particle and the direction of the magnetic field. Electromagnetic FieldsAn electromagnetic field is created by the interaction of an electric field and a magnetic field. Electromagnetic fields have both electric and magnetic components, and they travel through space at the speed of light. Electromagnetic waves are a form of electromagnetic radiation that carries energy. Electromagnetic radiation includes radio waves, microwaves, infrared light, visible light, ultraviolet light, X-rays, and gamma rays.Maxwell's EquationsMaxwell's equations describe the behavior of electric and magnetic fields. They are a set of partial differential equations that relate the electric and magnetic fields to the electric charges and currents that are present. The equations describe how an electric field can produce a magnetic field, and a magnetic field can produce an electric field. They also describe how the electromagnetic fields propagate through space.Electromagnetic WavesElectromagnetic waves are waves of energy that are propagated through space by the interaction of electric and magnetic fields. Electromagnetic waves do not require any medium to propagate through. They can travel through a vacuum, which is why they are also known as vacuum waves.Electromagnetic waves are classified based on their frequency and wavelength. Radio waves have the lowest frequency, and gamma rays have the highest frequency. Radio waves have the longest wavelength, and gamma rays have the shortest wavelength.Applications of ElectromagnetismElectromagnetism has many practical applications in our daily lives. Some of the most common applications include electric motors, generators, transformers, telecommunication devices, medical imaging devices, and microwave ovens. Electromagnetism has also played a significant role in the development of modern technology, including computers, television, radio, and mobile phones.ConclusionElectromagnetism is a fascinating field of physics that has wide-ranging applications in our daily lives. This course provides students with a comprehensive understanding of electric and magnetic fields, electromagnetic radiation, and electromagnetic waves. By studying electromagnetism, students can gain a deeper appreciation for the fundamental principles that govern the behavior of the universe around us.Electromagnetism is one of the four fundamental forces of nature, along with gravity, strong nuclear force, and weak nuclear force. It is a field of physics with numerous applications in our modern society. Without the understanding of electromagnetism, we would not have the modern comforts that we have today, including electricity, the internet, cell phones, and many other devices.One of the most significant contributions of electromagnetism to modern society is the use of electric motors. Electric motors are devices that convert electrical energy into mechanical energy.They are used in a wide range of applications, from household appliances to transportation systems. The underlying principle of electric motors is electromagnetic induction, which is the process of inducing an electric current in a conductor by varying the magnetic field around it.Another important application of electromagnetism is in generators. Generators are devices that convert mechanical energy into electrical energy. They are often used in power plants to generate electricity that is distributed to homes and businesses. The principle of electromagnetic induction is also used in generators. When a conductor moves through a magnetic field, an electric current is induced in the conductor.Electromagnetism also plays a central role in the functioning of transformers. A transformer is a device that changes the voltage of an alternating current (AC) power supply. Transformers are used to step up or step down the voltage of an AC power supply. They are used in power grids to maintain a constant voltage throughout the grid. The principle used in transformers is electromagnetic induction, with the primary and secondary coils of wire interacting with the magnetic field to produce the desired voltage change. Telecommunication devices, including radios, televisions, and cell phones, also rely on the principles of electromagnetism. The radio waves used for communication are a form of electromagnetic radiation. Radio waves are used to transmit and receive signals between devices. The workings of these devices depend on the principles of electromagnetic induction and electromagnetic radiation.In addition to powering devices, electromagnetism is used in medical imaging devices. Magnetic resonance imaging (MRI) machines use magnetic fields and radio waves to produce images of the body's internal structures. The patient is placed in a powerful magnetic field, which causes the protons in their body to align with the field. A radio wave is then sent through the body, causing the protons to produce a signal. The signal is detected, and an image is produced based on the strength and location of the signal.Microwave ovens are another example of electromagnetism in action. These appliances use microwaves to cook food. Microwaves are a type of electromagnetic radiation with a frequency of around 2.4 GHz. The microwaves cause the water molecules in the food to vibrate rapidly, producing heat. This heats the food quickly and evenly, making it a popular method for cooking.The study of electromagnetism has also led to the development of modern technology. Computers, televisions, radios, and cell phones all rely on the principles of electromagnetism. The development of these technologies has revolutionized the way we live and communicate. The internet, for example, would not exist without the principles of electromagnetism.In conclusion, electromagnetism is a fascinating field of physics with numerous practical applications in our daily lives. It is the foundation of modern technology, and our society would not be the same without it. By studying electromagnetism, we can gain a deeper understanding of the world around us and appreciate thefundamental principles that govern our universe. As technology advances, we can expect even more exciting and innovative applications of electromagnetism in the years to come.。
Ilya Prigogine---Structure, Dissi’pation and Life（伊利亚·普里高津---结构、耗散和生命）•In the history of modern natural science, there are three milestones which attract worldwide attention:•The first one is classical me’chanics associated with the name of the scientific giant Newton;•The second one is Relativity Theory Associated with Einstein's Name, the Founder of Modern Physics；•（在现代自然科学史上，有三个里程碑引起了全世界的注意：•第一个是与科学巨人牛顿的名字相关的经典力学；••第二个是相对论，与现代物理学的奠基人爱因斯坦的名字联系在一起；）•The third one is quantum mechanics associated with the names of Bohr, Heisenberg and others.•（第三个是与玻尔、海森堡等名字相关的量子力学。
）•••For decades, scientists all over the world have been looking up to the peak of science while looking forward to the rise of another giant monument, Ilya Prigogine----A physicist who views the world from the perspective of evolution. •（•几十年来，全世界的科学家都在仰望科学的巅峰，同时期待着另一座巨大的纪念碑——从进化的角度看待世界的物理学家伊利亚·普里高津的崛起。
