Let’s learn about colors

We live in a colorful world. Green leaves spring from the trees, flowers come in every color of the rainbow, and birds sport fashionably colorful feathers. We even live on a pale blue dot.

What creates all this color? Electromagnetic radiation — waves of energy moving through space. The waves come in different lengths. Cells in the backs of our eyes can perceive light as black, white, red, green or blue. The cells then relay that information to the brain — and we see the world in color. But we don’t see every color. Many wavelengths are beyond what humans can see.Nature has come up with many ways to make colors. Leaves, for instance, get their green from chlorophyll — the same chemical that helps them make sugar from sunlight. Some beetles, though, are beautifully shimmery from tiny structures in their wings. Those structures bounce light off differently at each angle, producing iridescence. And peacock spiders use a combination of pigments and tiny structures to get their beautiful behinds.

Power words

angle: The space (usually measured in degrees) between two intersecting lines or surfaces at or close to the point where they meet.

beetle: An order of insects known as Coleoptera, containing at least 350,000 different species. Adults tend to have hard and/or horn-like “forewings” which covers the wings used for flight.

birds: Warm-blooded animals with wings that first showed up during the time of the dinosaurs. Birds are jacketed in feathers and produce young from the eggs they deposit in some sort of nest. Most birds fly, but throughout history there have been the occasional species that don’t.

cell: The smallest structural and functional unit of an organism. Typically too small to see with the unaided eye, it consists of a watery fluid surrounded by a membrane or wall. Depending on their size, animals are made of anywhere from thousands to trillions of cells. Most organisms, such as yeasts, molds, bacteria and some algae, are composed of only one cell.

chemical: A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H2O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.

chlorophyll: Any of several green pigments found in plants that perform photosynthesis — creating sugars (foods) from carbon dioxide and water.

electromagnetic: An adjective referring to light radiation, to magnetism or to both.

electromagnetic radiation: Energy that travels as a wave, including forms of light. Electromagnetic radiation is typically classified by its wavelength. The spectrum of electromagnetic radiation ranges from radio waves to gamma rays. It also includes microwaves and visible light.

hue: A color or shade of some color.

iridescent: Adjective that describes something that seems to change color with a shift in the angle at which it is viewed or at which lighting is applied.

pigment: A material, like the natural colorings in skin, that alter the light reflected off of an object or transmitted through it. The overall color of a pigment typically depends on which wavelengths of visible light it absorbs and which ones it reflects. For example, a red pigment tends to reflect red wavelengths of light very well and typically absorbs other colors. Pigment also is the term for chemicals that manufacturers use to tint paint.

radiant: (adj.) A term for something that is radiated, such as heat or some other type of radiation. (n.) The point or object from which light or heat radiates (such as the heating element in an electric heater). Or the point from which objects (such as meteors) appear to come.

radiation: (in physics) One of the three major ways that energy is transferred. (The other two are conduction and convection.) In radiation, electromagnetic waves carry energy from one place to another. Unlike conduction and convection, which need material to help transfer the energy, radiation can transfer energy across empty space.

robot: A machine that can sense its environment, process information and respond with specific actions. Some robots can act without any human input, while others are guided by a human.

spider: A type of arthropod with four pairs of legs that usually spin threads of silk that they can use to create webs or other structures.

wave: A disturbance or variation that travels through space and matter in a regular, oscillating fashion.

wavelength: The distance between one peak and the next in a series of waves, or the distance between one trough and the next. It’s also one of the “yardsticks” used to measure radiation. Visible light — which, like all electromagnetic radiation, travels in waves — includes wavelengths between about 380 nanometers (violet) and about 740 nanometers (red). Radiation with wavelengths shorter than visible light includes gamma rays, X-rays and ultraviolet light. Longer-wavelength radiation includes infrared light, microwaves and radio waves.

Electron

 Electron

This is one of the three types of particles that make up an atom. The other two are protons and neutrons. Protons and neutrons form the center, or nucleus, of an atom. Electrons exist in a surrounding cloud. They swarm around the center of the atom. That’s because electrons have negative electric charge. That makes them attracted to the positively charged protons in the nucleus. Normally, atoms have the same number of electrons as protons. So the atoms are electrically neutral.

Unlike protons and neutrons, electrons don’t contain smaller particles. That is, they are fundamental particles. Each electron is extremely small. Its mass is only about 1/1,800 the mass of a proton or neutron. Still, electrons play an important role in how atoms behave. Atoms of different elements hold their electrons in different arrangements around the nucleus. That arrangement gives each element its distinct properties. For instance, it determines how well an element conducts electricity. It also determines the temperature at which the element boils. And, that arrangement governs how likely atoms are to share electrons with each other. When atoms share electrons, they link together and form molecules.

Power words

atom: The basic unit of a chemical element. Atoms are made up of a dense nucleus that contains positively charged protons and uncharged neutrons. The nucleus is orbited by a cloud of negatively charged electrons.

cloud: A plume of molecules or particles, such as water droplets, that move under the action of an outside force, such as wind, radiation or water currents. 

electric charge: The physical property responsible for electric force; it can be negative or positive.

electron: A negatively charged particle, usually found orbiting the outer regions of an atom; also, the carrier of electricity within solids.

fundamental: Something that is basic or serves as the foundation for another thing or idea.

ion: (adj. ionized) An atom or molecule with an electric charge due to the loss or gain of one or more electrons. An ionized gas, or plasma, is where all of the electrons have been separated from their parent atoms.

link: A connection between two people or things.

mass: A number that shows how much an object resists speeding up and slowing down — basically a measure of how much matter that object is made from.

matter: Something that occupies space and has mass. Anything on Earth with matter will have a property described as "weight."

molecule: An electrically neutral group of atoms that represents the smallest possible amount of a chemical compound. Molecules can be made of single types of atoms or of different types. For example, the oxygen in the air is made of two oxygen atoms (O2), but water is made of two hydrogen atoms and one oxygen atom (H2O).

neutron: A subatomic particle carrying no electric charge that is one of the basic pieces of matter. Neutrons belong to the family of particles known as hadrons.

nucleus: Plural is nuclei. (in physics) The central core of an atom, containing most of its mass.

particle: A minute amount of something.

plasma: (in chemistry and physics) A gaseous state of matter in which electrons separate from the atom. A plasma includes both positively and negatively charged particles.

proton: A subatomic particle that is one of the basic building blocks of the atoms that make up matter. Protons belong to the family of particles known as hadrons.

INTRODUCTION to Physics

INTRODUCTION to Physics

 Without the science of physics and the work of physicists, our modern ways of living would not exist. Instead of having brilliant, steady electric light, we would have to read by the light of candles, oil lamps, or at best, flickering gaslight. We might have buildings several stories high, but there could be no hope of erecting an Empire State Building. We could not possibly bridge the Hudson River or the Golden Gate much less build a jet plane, use a cell phone, or watch a television show. The personal computer would be unimaginable.

All other natural sciences depend upon physics for the foundations of their knowledge. Physics holds this key position because it is concerned with the most fundamental aspects of matter and energy and how they interact to make the physical universe work. For example, modern physics has discovered how atoms are made up of smaller particles. It has also revealed how these particles interact to join atoms into molecules and larger masses of matter. Chemists use this knowledge to guide them in their work in studying all existing chemical compounds and in making new ones.

Biologists and medical researchers in turn use both physics and chemistry in studying living tissues and in developing new drugs and treatments. Furthermore their electrical equipment, microscopes, X-rays, and many other aids and the use of radioactivity were developed originally by physicists.

Physicists have also led in bringing people to think in scientific ways. What we call the scientific method had its real beginnings some four centuries ago in many fields of knowledge. The most impressive of the early triumphs came in physics and in its application to astronomy for studying the motions of the Sun, Moon, planets, and stars.

Galileo made the first real contributions, in the late 16th and early 17th century. He discovered the natural laws that govern falling bodies and the swinging of the pendulum. Shortly after this, Johannes Kepler established the three laws that explain all the motions of the planets. Finally, in the late 17th century Isaac Newton explained these results by establishing the law of gravitation. This law applies invariably to all matter in the universe—whether it is as small as a grain of sand or as large as the Sun. This triumph of explaining a vast range of phenomena with a single law inspired workers in all fields of knowledge to trust scientific methods.

This revolution in understanding was greatly aided by concurrent advances in technology. Instruments such as clocks, barometers (which measure the pressure of the atmosphere), and telescopes were invented and improved. For example, Galileo, Kepler, and Newton made contributions to the development of telescopes and thus gave astronomy a powerful instrument with which to work.

There is no exact distinction between physics and other natural sciences because all sciences overlap. In general, however, physics deals with phenomena that pertain to all classes of matter and energy. Physicists try to discover the most basic laws of nature, which underlie and often explain those of other fields of science.

One major branch of physics, mechanics, deals with the states of matter—solids, liquids, and gases—and with their motions. The pioneer achievements of Galileo, Kepler, and Newton dealt with solid masses of matter in motion. Such studies are a part of the subdivision of mechanics called dynamics, the study of matter in motion. This wide-ranging topic includes not only the motions of stars and baseballs but also those of gyroscopes, of the water pumped by a fire engine (hydrodynamics), and of the air passing over the wings and through the jet engine of an airplane (aerodynamics).

The other great subdivision of mechanics is statics, the study of matter at rest. Statics deals with the balancing of forces with appropriate resistances to keep matter at rest. The design of buildings and of bridges are examples of problems in statics.

Other divisions of physics are based on the different kinds of energy that interact with matter. They deal with electricity and magnetism, heat, light, and sound. From these branches of physics have come clues that have revealed how atoms are constructed and how they react to various kinds of energy. This knowledge is often called the basis of modern physics. Among the many subdivisions of modern physics are electronics and nuclear physics.

Physics is closely related to engineering. A person who uses physical principles in solving everyday problems is often called an engineer. For example, electricity is one of the subdivisions of physics; one who uses the natural laws of electricity to help in designing an electric generator is an electrical engineer.

Newton's 3 Laws of Motion for Kids: Three Physical Laws of Mechanics for Children - FreeSchool

 

How does your mobile phone work?

 

Introduction to the Major Laws of Physics

 Over the years, one thing scientists have discovered is that nature is generally more complex than we give it credit for. The laws of physics are considered fundamental, although many of them refer to idealized or theoretical systems that are hard to replicate in the real world.

Like other fields of science, new laws of physics build on or modify existing laws and theoretical research. Albert Einstein's theory of relativity, which he developed in the early 1900s, builds on the theories first developed more than 200 years earlier by Sir Isaac Newton.

Law of Universal Gravitation

Sir Isaac Newton's groundbreaking work in physics was first published in 1687 in his book "The Mathematical Principles of Natural Philosophy," commonly known as "The Principia." In it, he outlined theories about gravity and of motion. His physical law of gravity states that an object attracts another object in direct proportion to their combined mass and inversely related to the square of the distance between them.

Three Laws of Motion

Newton's three laws of motion, also found in "The Principia," govern how the motion of physical objects change. They define the fundamental relationship between the acceleration of an object and the forces acting upon it.

• First Rule: An object will remain at rest or in a uniform state of motion unless that state is changed by an external force. 
• Second Rule: Force is equal to the change in momentum (mass times velocity) over time. In other words, the rate of change is directly proportional to the amount of force applied. 
• Third Rule: For every action in nature there is an equal and opposite reaction. 

Together, these three principles that Newton outlined form the basis of classical mechanics, which describes how bodies behave physically under the influence of outside forces.

Conservation of Mass and Energy

Albert Einstein introduced his famous equation E = mc2 in a 1905 journal submission titled, "On the Electrodynamics of Moving Bodies." The paper presented his theory of special relativity, based on two postulates:

• Principle of Relativity: The laws of physics are the same for all inertial reference frames. 
• Principle of Constancy of the Speed of Light: Light always propagates through a vacuum at a definite velocity, which is independent of the state of motion of the emitting body.

The first principle simply says that the laws of physics apply equally to everyone in all situations. The second principle is the more important one. It stipulates that the speed of light in a vacuum is constant. Unlike all other forms of motion, it is not measured differently for observers in different inertial frames of reference.

Laws of Thermodynamics

The laws of thermodynamics are actually specific manifestations of the law of conservation of mass-energy as it relates to thermodynamic processes. The field was first explored in the 1650s by Otto von Guericke in Germany and Robert Boyle and Robert Hooke in Britain. All three scientists used vacuum pumps, which von Guericke pioneered, to study the principles of pressure, temperature, and volume.

• The Zeroeth Law of Thermodynamics makes the notion of temperature possible.
• The First Law of Thermodynamics demonstrates the relationship between internal energy, added heat, and work within a system.
• The Second Law of Thermodynamics relates to the natural flow of heat within a closed system.
• The Third Law of Thermodynamics states that it is impossible to create a thermodynamic process that is perfectly efficient.

Electrostatic Laws

Two laws of physics govern the relationship between electrically charged particles and their ability to create electrostatic force and electrostatic fields. 

• Coulomb's Law is named for Charles-Augustin Coulomb, a French researcher working in the 1700s. The force between two point charges is directly proportional to the magnitude of each charge and inversely proportional to the square of the distance between their centers. If the objects have the same charge, positive or negative, they will repel each other. If they have opposite charges, they will attract each other.
• Gauss's Law is named for Carl Friedrich Gauss, a German mathematician who worked in the early 19th century. This law states that the net flow of an electric field through a closed surface is proportional to the enclosed electric charge. Gauss proposed similar laws relating to magnetism and electromagnetism as a whole.

Beyond Basic Physics

In the realm of relativity and quantum mechanics, scientists have found that these laws still apply, although their interpretation requires some refinement to be applied, resulting in fields such as quantum electronics and quantum gravity.

The Basics of Physics in Scientific Study

 Physics is a systematic study of the natural world, particularly the interaction between matter and energy. It is a discipline that attempts to quantify reality through a precise application of observation coupled with logic and reason.

In order to make use of such a discipline, you must first understand certain fundamentals. Only by learning the basics of physics can you build upon it and dive deeper into this field of science. Whether you are pursuing a career in physics or merely interested in its findings, it certainly is fascinating to learn about.

What Is Considered Physics?

To begin the study of physics, you must first understand what physics actually means. Understanding what falls within the realm of physics—and what does not—helps focus the field of study so you can formulate meaningful physics questions.

Behind every question in physics lies four very important terms you will want to understand: hypothesis, model, theory and law. 

Physics can be either experimental or theoretical. In experimental physics, physicists address a scientific problem using techniques such as the scientific method in an attempt to prove a hypothesis. Theoretical physics is often more conceptual in that physicists are focused on developing scientific laws, such as the theory of quantum mechanics. 

These two forms of physics are related to each other and connected to other forms of scientific study. Quite often, experimental physics will test the hypotheses of theoretical physics. Physicists themselves can specialize in a variety of fields, from astronomy and astrophysics to mathematical physics and nanotechnology. Physics also plays a role in other fields of science, such as chemistry and biology.

The Fundamental Laws of Physics

The goal of physics is to develop precise models of physical reality. The best case scenario is to develop a series of very fundamental rules to describe how these models function. These rules are frequently called "laws" after they have been used successfully for many years.

Physics is complicated, but it does fundamentally rely on a number of accepted laws of nature. Some are historical and groundbreaking discoveries in science. These include Sir Isaac Newton's Law of Gravity as well as his Three Laws of Motion. Albert Einstein's Theory of Relativity and the laws of thermodynamics also fall into this category.

Modern physics is building off those monumental truths to study things such as quantum physics which explores the invisible universe. Similarly, particle physics seeks to understand the smallest bits of matter in the universe. This is the field where strange words like quarks, bosons, hadrons, and leptons enter the scientific dialogue that makes headlines today.

The Tools Used in Physics

The tools that physicists use range from the physical to the abstract. They include balance scales and laser beam emitters as well as mathematics. Understanding this wide range of tools and the methods for applying them is essential to understanding the process that physicists go through in studying the physical world.

The physical tools include things like superconductors and synchrotrons, which are used to create intense magnetic fields. These can be applied in studies like the Large Hadron Collider or practically in the development of magnetic levitation trains.

Mathematics is at the heart of physics and is vital in all fields of science. As you begin to explore physics, fundamentals such as using significant figures and going beyond the basics of the metric system will be important. Math and physics go much deeper as well and concepts like vector mathematics and the mathematical properties of waves are crucial to the work of many physicists.

History's Famous Physicists

Physics does not exist in a vacuum (even though some physics is practiced in an actual vacuum). The forces of history have shaped the development of physics as much as any other field in history. Quite often, it is useful to understand the historical perspectives which led to our current understanding. That includes the ​many incorrect paths that were faltered along the way.

It is also useful and intriguing to learn about the lives of the famous physicists of the past. The ancient Greeks, for instance, combined philosophy with the study of natural laws and are particularly known for an interest in astronomy.

In the 16th and 17th centuries, Galileo Galilei further studied, observed, and experimented with the laws of nature. Though he was persecuted in his time, he is regarded today as "the father of science" (coined by Einstein) as well as modern physics, astronomy, and observational science.

Galileo inspired and was followed by famous scientists like Sir Isaac Newton, Albert Einstein, Niels Bohr, Richard P. Feynman, and Stephen Hawking. These are just a few of the names of physics history that have shaped our understanding of how our world works. Their abilities to challenge accepted theories and devise new ways of looking at the universe have inspired physicists who continue to achieve scientific breakthroughs.