Applied Physics: Electromagnetism

• Applied physics is the practical application of physics principles to solve real-world problems
• It bridges the gap between pure physics research and engineering applications
• Applied physicists may work in various fields, including materials science, optics, electronics, and medical physics

Electromagnetism

• Electromagnetism is the study of the electromagnetic force, one of the four fundamental forces of nature
• It describes how electrically charged particles interact with each other via electric and magnetic fields
• Key concepts include electric charge, electric field, magnetic field, and electromagnetic waves
• Electric charge is a fundamental property of matter that can be positive or negative
• Like charges repel, and opposite charges attract
• The electric field is a vector field that describes the force exerted on a positive test charge at a given point
• It is created by electric charges
• The magnetic field is a vector field that describes the force exerted on a moving charge at a given point
• It is created by moving electric charges or magnetic materials
• Electromagnetic waves are disturbances in electric and magnetic fields that propagate through space
• They include radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays
• Maxwell's equations are a set of four equations that describe the behavior of electric and magnetic fields and their relationship to electric charges and currents
• These equations are fundamental to the understanding of electromagnetism
• Electromagnetic induction is the production of an electromotive force (EMF) across an electrical conductor in a changing magnetic field
• This principle is used in electric generators and transformers
• Capacitance is the ability of a body to store an electrical charge
• It is measured in farads (F)
• Inductance is the property of an electrical conductor by which a change in current through it induces an electromotive force (voltage) in both the conductor itself and in any nearby conductors
• It is measured in henries (H)
• Impedance is the measure of opposition that a circuit presents to a current when a voltage is applied
• It includes resistance, inductance, and capacitance

Optics

• Optics is the study of light and its behavior
• It encompasses phenomena such as reflection, refraction, diffraction, interference, and polarization
• Geometrical optics deals with light as rays and uses geometry to analyze optical systems
• Reflection is the bouncing back of light when it strikes a surface
• The law of reflection states that the angle of incidence equals the angle of reflection
• Refraction is the bending of light as it passes from one medium to another
• Snell's law describes the relationship between the angles of incidence and refraction and the refractive indices of the two media
• Lenses are optical devices that refract light to form images
• Converging lenses focus light, while diverging lenses spread light
• Mirrors are optical devices that reflect light to form images
• Plane mirrors produce virtual images, while curved mirrors can produce real or virtual images
• Wave optics considers the wave nature of light and explains phenomena such as interference and diffraction
• Interference is the superposition of two or more waves, resulting in constructive or destructive interference patterns
• Diffraction is the bending of waves around obstacles or through narrow openings
• Huygens' principle states that every point on a wavefront can be considered as a source of secondary spherical wavelets
• These wavelets combine to form a new wavefront
• Polarization is the property of light waves that describes the orientation of the electric field vector
• Unpolarized light has electric field vectors in random directions, while polarized light has electric field vectors in a specific direction
• Quantum optics studies the particle nature of light (photons) and its interaction with matter
• The photoelectric effect is the emission of electrons from a material when light shines on it
• This effect demonstrates the particle nature of light
• Lasers are devices that produce coherent and monochromatic light beams
• Coherent light waves have the same phase and direction
• Monochromatic light consists of a single wavelength
• Optical fibers are thin strands of glass or plastic that transmit light over long distances
• Total internal reflection is the principle behind optical fiber transmission
• Applications of optics include lenses, microscopes, telescopes, cameras, lasers, and optical fibers
• Microscopy is the technique of using microscopes to view objects that are too small to be seen with the naked eye
• Telescopes are instruments used to observe distant objects by collecting and focusing electromagnetic radiation
• Cameras are devices used to capture images by focusing light onto a sensor