Application of Physics in Other Fields Notes

Application of Physics in Other Fields

Introduction

• Science is the collection of different types of scientific fields.
• It is the union of these fields that helps to understand nature.

Physics and Other Fields

• Physics is a science that deals with matter, energy, and their interactions.
• It is the most essential and all-inclusive of other sciences.
• Physics has a strong influence on all scientific development.

Relation of Physics with Chemistry

• Physics and chemistry are similar as they both study matter.
• Chemistry studies the composition of matter, while physics studies how matter interacts.
• They are both physical sciences, and the areas overlap at times.
• Spectroscopy techniques are developed by collaborative work of physicists and chemists.
• Spectroscopy is the study of the interaction between matter and electromagnetic radiation as a function of wavelength or frequency.
• The study of matter and electricity in physics provides the groundwork for understanding concepts in chemistry, such as:
  • Atomic structure
  • Molecular structure
  • X-ray diffraction
  • Radioactivity
  • Periodic properties of elements
• Chemistry is rooted in atomic and molecular physics.

Relation of Physics and Biology

• To understand how life works, it is essential to understand physics.
• Physics explains various aspects of the human body:
  • Mechanics of human motion
  • Energetics of metabolism
  • Fluid dynamics of blood flow through vessels
  • Mechanisms of speaking and hearing
  • Optical imaging
• Newtonian mechanics explains how different animals and their body parts move.
• The union of physics and biology helps to explain how athletes run fast.
• Newtonian mechanics states that a body is in stable equilibrium under the action of gravity if its center of mass is directly over its base of support.

Physics, Fluid Flow, and Biology

• In physics, fluid flow, the equation of continuity, and turbulent flow are crucial in understanding the circulation of blood and blood pressure in multicellular organisms.
• Soft-bodied animals, such as earthworms, use Pascal's principle to produce body motion, lacking a firm skeleton.

Physics of Sound Waves and Biology

• Sound is a mechanical wave produced by vibrating bodies which generate sound waves.
• When human vocal cords vibrate, the surrounding air molecules are disturbed and forced to follow the motion of the vibrating body, propagating sound from the source.

Physics of Electricity and Biology

• Many life processes involve electrical phenomena.
• The nervous system of animals and the control of muscle movement are governed by electrical interaction.
• Electrical phenomena in living organisms are found in specialized cells called neurons.
• Neurons are a complex network that receive, process, and transmit information from one part to another.
• The center of the network is located in the brain, which has the ability to store and analyze information.
• While awake, the brain produces 10-23 W of power, enough to power a light bulb.

Optical Physics and Biology

• Light is the electromagnetic radiation in the wavelength region between 400nm and 700nm.
• Light is a tiny part of the electromagnetic spectrum, which is very important in physics and biology. In photosynthesis, plants use light to convert carbon dioxide and water to organic material.
• Animals have evolved light-sensitive organs like eyes, which are the main sources of information about the surrounding environment.

Physics and Astronomy

• Astrophysics is the study of the physics of heavenly objects, called astronomical objects.
• It includes the study of the solar system and its constituents, the properties, birth, life, and death of stars, dust, galaxies, and the whole universe.
• Newton's law of motion and gravitation describe the motion of the moon around planets and the motion of planets around the sun.

Physics of Electromagnetic Waves and Astronomy

• Astronomers collect information about the radiation from space objects to study:
  • The birth and death of stars.
  • How hot the objects are.
  • How far away they are.
  • How the universe is formed.
• Astronomers use different types of telescopes to detect different parts of the electromagnetic spectrum:
  • Radio telescope
  • Infrared telescope
  • Optical telescope
• The colors that can be observed on the image are false colors because radiation detected is turned into an image by computers.
• Astronomers use light to measure the distance of astronomical objects.
• Astronomers also use light-years as an alternate astronomical distance measuring unit.
• A light-year is the distance that light travels in one year.
• apparent brightness \propto \frac{true brightness}{distance^2}
• True brightness is known as luminosity.

Physics of Atoms and Astronomy

• Atomic astrophysics is concerned with performing atomic physics calculations that will be useful to astronomers.
• Physics that explains the emission and absorption of radiation is closely related to the structure and energies of individual atoms that form the astronomical objects.
• When electrons of an atom jump from a higher to a lower atomic orbit, a photon is emitted.
• When electrons jump from a lower electron orbit to a higher one, a photon is absorbed.
• Emission and absorption of radiation depend on the characteristics of individual atoms and help to measure:
  • Composition
  • Temperature
  • Motion of stars and their spectra.

Physics and Geology

• Geology is a branch of earth science that studies the solid and liquid matter that makes up the Earth and the different processes on this matter.
• Geology uses physics concepts to study the following properties of rocks and minerals:
  • Electrical properties
  • Magnetization
  • Radioactivity and elastic properties
• Geologists can study different properties of rocks and minerals by sending different types of waves from the surface of the earth without excavation.
• Mineralogists study the composition and structure of minerals.

Physics and Engineering

• Physics generates fundamental knowledge that can be used by different branches of engineering, such as civil, mechanical, electrical, chemical, etc., governed by physical laws.
• Civil engineering concerns designing and building skyscrapers, roads, bridges, dams, and railways using physics knowledge of force, fluid pressure, gravity, and other related principles.
• Mechanical engineering uses knowledge of mathematics, physics, and material science to create engines, vehicles, weapons, and other manufacturing equipment.
• Electrical engineering involves designing electrical circuits including motors, electronics appliances, optical fiber networks, computers and communication links using physics concepts like electromagnetism, mechanics, thermodynamics, and others.

Medical Physics

• Medical physics is the branch of physics that deals with the application of principles of physics to medical diagnosing and treating abnormal tissues.
• Different modern medical diagnosis devices include:
  • X-ray
  • Magnetic resonance imaging (MRI)
  • X-ray computerized tomography (CT) scan
  • Stethoscope
  • Ultrasound
• X-rays are a form of electromagnetic radiation.
• X-rays have higher energy and can pass through most objects, including bodies.
• They are used to look at bones and joints.

Magnetic Resonance Imaging (MRI)

• MRI is a large cylindrical tube-shaped machine that creates a strong magnetic field around the patient and sends a pulse of radio waves from a scanner.
• It uses the body’s natural magnetic properties to produce detailed images from any part of the body.
• For imaging purposes, the hydrogen nucleus (a single proton) is used because of its abundance in water and fat.
• The strong magnetic field created by the MRI scanner causes the atoms in our body to align in the same direction. Then radio waves are sent from the MRI to the computer.

X-Ray Computerized Tomography (CT) Scan

• It is a computerized X-ray imaging procedure in which a narrow beam of X-rays is aimed at a patient and quickly rotates around the body, producing signals that are processed by machines and computers to generate cross-sectional images.
• CT scan images provide more detailed information than normal X-rays.

Stethoscope

• It is a medical instrument for listening to the action of someone’s heart, lungs, or breathing.
• It is a small disc-shaped resonator that is placed on the chest, with two tubes connected to the doctor’s ears.

Ultrasound

• It is an imaging test that uses sound waves to make pictures of organs, tissues, and other structures inside our body.
• If the frequency of sound is higher than 20 KHz, it is called ultrasound or ultrasonic.
• An ultrasound machine sends an ultrasound wave into a body tissue and detects the reflected wave.
• An ultrasound image is commonly described by three words:
  • Anechoic
  • Hypoechoic
  • Hyperechoic
• Anechoic: These areas appear black on ultrasound due to echoless regions, which result from fluid-filled regions.
• Hypoechoic: These areas appear dark gray.
• Hyperechoic: These areas bounce back many sound waves and appear as light gray on an ultrasound image.

Radiation Therapy

• Radiation therapy is a cancer treatment that uses high doses of radiation to kill cancer cells and shrink tumors.

Physics and Defense Technology

• Modern defense forces have different branches: Air Force, Army, Navy, and Space Force.
• All of these defense forces demand different knowledge and advanced physics like laser-guided satellite technology, modern electronics, optics, atomic and nuclear physics, etc.

Radar Technology

• RADAR is derived from the phrase “radio detection and ranging.”
• It applies to electronic equipment designed for detecting and tracking the presence of objects like ships, vehicles, aircraft, missiles, etc.
• To calculate the range:
• R = \frac{Ct}{2}
• RADAR is used in military purposes; its major function is to detect targets and guide defensive and offensive weapons.
• RADAR has civilian applications, such as controlling air traffic, weather sensing from remote areas, and planetary observation.

Missile Technology

• A missile is a rocket-propelled or jet-propelled weapon designed to deliver an explosive weapon with great accuracy and high speed.
• Missiles are of different types:
  • Cruise missile
  • Ballistic missile
• Cruise missiles are jet-propelled throughout their flights.
• Ballistic missiles are rocket-powered only in the initial phase of flight, with the influence of gravity and air resistance force following an arc trajectory to the target.

Infrared Wave Detection for Night Vision

• Infrared (IR) devices typically use heat emission to identify objects that cannot be detected using available light sources.
• IR is used for military purposes like night vision, navigation, hunting, hidden object detection, and targeting.

Physics in Communication

• Today our lives would be very difficult without the use of communication technology like telephone, mobile devices, and computers.

Communication

• Communication is transferring information from one point to another point.
• To transfer information, the following is required:
  • Receiver
  • Medium
  • Transmission
• Communication systems can be classified as wired and wireless.
• Wireless communications include:
  • Satellite communication
  • Ground wave communication
  • Microwave
  • Infrared
  • Radio wave
• Wire communication systems include wire and optical fiber.