physics test ch. 30-36

Atomic Models, Quantum Mechanics

Atomic Models: A complex arrangement of negatively charged electrons arranged in defined shells about a positively charged nucleus. This nucleus contains most of the atom's mass and is composed of protons and neutrons (except for common hydrogen which has only one proton) Quantum Mechanics: describes how the Universe works at the level smaller than atoms.

Radioactivity & Rays, Half-Life, Transmutation & Dating

RADIOACTIVITY: the particles which are emitted from nuclei as a result of nuclear instability. Because the nucleus experiences the intense conflict between the two strongest forces in nature, it should not be surprising that there are many nuclear isotopes which are unstable and emit some kind of radiation. RAYS: an idealized model of light, obtained by choosing a line that is perpendicular to the wavefronts of the actual light, and that points in the direction of energy flow. Half-Life: the time required for a quantity to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo, or how long stable atoms survive, radioactive decay. TRANSMUTATION: conversion of one chemical element into another. The bombarding of elements with protons or nuetrons to make a new element. A transmutation entails a change in the structure of atomic nuclei and hence may be induced by a nuclear reaction, such as neutron capture, or occur spontaneously by radioactive decay, such as alpha decay and beta decay In radioactive decay, an atom will lose protons, and therefore forms new elements. In alpha decay, an alpha particle (a helium nucleus) is emitted from the radioactive atom, and the atom therefore loses 2 protons, and becomes a new element. a decaying element emits rays, alpha, beta, and gamma rays. DATING: any method of determining the age of earth materials or objects of organic origin based on measurement of either short-lived radioactive elements or the amount of a long-lived radioactive element plus its decay product.

The atom model, Rutherford gold experiment

-BOHR'S model: The Bohr model helped described different light spectrums caused by electrons. an atom almost works like our solar system. We revolve around the sun the same way electrons revolve around a nucleus. There are different levels of electron rings that are all slightly apart from each other. electrons have to be on one of those levels, it can't be in between. Electrons move up or down levels depending if they get hit by a high energy photon or they emit/release photons. rutherford figured out atoms have a nucleus. JJ Thomas found the electron

Relativity, fission, fusion, mass energy equivalence

-Fission: spitting bigger element/atom into smaller elements/atoms. Usually, neutrons fly in the hit the nucleus of the element which causes it to split. Nuclear power plants use fission. Fusion: to combine smaller elements/atoms to make bigger elements/atoms. This lead to the creation of the hydrogen bomb. A byproduct of this would be a new atom but also the loss of neutron, which releases a lot of energy. E=MC^2. E is energy, c is the speed of light. M is the mass defect which is the loss of mass after the reaction. ONE QUESTION ON TRANSMUTATION Special relativity: based on 2 assumptions called postulates. The two postulates are All laws of nature are valid in all inertia reference frame. Inertia frame meaning, if the frame does not accelerate. A reference frame is like how one thing compares to another. So like the speed of a car on earth, the earth being the frame of reference. The second postulate is the speed of light is always going to be the same no matter the inertia reference frame. When talking about relativity you need two things, the object being observed and the observer. Everything is relative but the motion of an object depends on who is the observer.

Light excitation & Photon

-LIGHT EXCITATION: Excitation, in physics, the addition of a discrete amount of energy (called excitation energy) to a system—such as an atomic nucleus, an atom, or a molecule—that results in its alteration, ordinarily from the condition of lowest energy (ground state) to one of higher energy (excited state). An electron can become excited if it is given extra energy, such as if it absorbs a photon, or packet of light, or collides with a nearby atom or particle. -PHOTON: It is the smallest piece of light, a packet of energy. a type of elementary particle. It is the quantum of the electromagnetic field including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless, and they always move at the speed of light in vacuum. higher frequency correlates with higher energy. Smaller wavelength has a higher frequency, they are inversely proportional. Low energy light is red. higher energy is blue light. LIght is made of photons. the energy of a photon depends on its wavelength or color. WATCH YOUTUBE spectrum question on the test. why does white light spread out individual colors. different light spectrums. -Continuous spectrum: shows all wavelengths of light without any spikes of darkness. caused by a hot/dense energy source. -Emission spectrum: Emission Spectra Spikes in the spectra due to atoms releasing photons at those wavelengths. Mostly darkness with a few spikes of color. caused by a hot low-density cloud of gas. -abSRoRBTION spectrum: Absorption Spectra Absorption lines are where light has been absorbed by the atom thus you see a dip in the spectrum. mostly continuous spectrum with a few dark spikes do to absorption. caused by hot/dense energy source passing by a cooler low density cloud of gas.

Emission Spectra, Absorption Spectra, Fluorescence & Phosphorescence

-PHOTON: -Emission Spectra: Spikes in the spectra due to atoms releasing photons at those wavelengths. -Absorption Spectra: Absorption lines are where light has been absorbed by the atom thus you see a dip in the spectrum -Fluorescence: The emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. NO glow in the dark. excited by uv light. So it does not glow in the dark but when a light is shone on it it gets even brighter. light must be uv. highlighter ink would be fluorescence. -PHOSPHORESCENCE: the emission of radiation in a similar manner to fluorescent. emission continues after excitation ceases. excited by visible light, give s you after glowing. It does glow in the dark. excited by the visible light Light is energy my dude. Red photons are less energetic than purple ones. When an atom emits a photon, it spends energy. This energy can be provided by electric, so a light bulb. The difference is that the glow of fluorescence stops right after the source of excitatory radiation is switched off, whereas for phosphorescence, an afterglow with durations of fractions of a second up to hours can occur

Fission & Fusion, Mass-Energy Equivalence,

FISSION: the splitting of the nucleus of an atom into nuclei of lighter atoms, accompanied by the release of energy. FUSION: the process that powers the sun and the stars. It is the reaction in which two atoms of hydrogen combine together, or fuse, to form an atom of helium. In the process some of the mass of the hydrogen is converted into energy. Mass-Energy Equivalence: this gave Mass-energy equivalence entails that the total mass of a system may change, although the total energy and momentum remain constant; for example, the collision of an electron and a proton annihilates the mass of both particles, but creates energy in the form of photons.

nuclear fission and fusion

Fission: The spliting of atomic nuclei. this is how nuclear power plants make energy. In this process, a neutron hits the nucleus splitting the nucleus. Each of them take a share of electrons of the original atom Neutrons are made to bombard the nuclei of heavy elements to split them in two. When this process occurs, a lot of energy is released. Strong ineraction or nuclear force works in the nucleas to keep all the protons suck together, remember like poles push eachother away. When that nuetron hits the nucleaus, it breaks the bond/force and it causes the neclues to release all that energy that was stored by the strong nuclear force. Fusion: atomic nuclei conjoined. the sun emits light do to this process. two light elements to form a heavier one, done with the hydrogen bomb originally. only works with smaller atoms. Strong force pushes protons of nuclei together and eventually they combine forming a new atom. This also involves the release of alot of energy, more than in nuclear fission.

Quantum, continuous

Higher frequency has higher energy and shorter wavelength. Adding energy to the particle speeds it up. -Quantum: Things are not continuous. -Continuous: -Uncertainty: Heisenbergs law states the more accurately we measure the velocity of a particle the less accurately we can measure its position in space. So we can know how fast something is moving but not also where it is at. Specifically, it says that the more accurately you measure the momentum (or velocity) of a particle, the less accurately you can know its position, and vice versa. Waves are like disturbances in space like ripples in a pond and particles exist in a single place at any instance in time. An objects wave length is related to its momentum. We can measure the momentum of a wave but it has no position while we can know the position of a particle but it doesn't have a wavelength so we don't know its momentum. so if you add move waves(smaller wave packet) you better know the position but it creates a bigger momentum uncertainty and to know the momentum you add less waves(larger wave packet) but this creates a bigger wave position uncertainty. -IS light a PARTICLE or a WAVE?: Light acts like a wave when traveling and it acts like a particle when it is emitted from a source or landed on a film. Essentially it acts like both, wave-particle duality. The double slit experiment proves that light acts like a wave. -PHOTOELECTRIC EFFECT: proves why light acts like a particle. Energy of light solely depends on frequency not intensity. Higher intensity just means more particles but not more energy.

Length Contraction, Principle of Equivalence, Gravity Bends Light

Length Contraction: the phenomenon that a moving object's length is measured to be shorter than its proper length, which is the length as measured in the object's own rest frame. So a person on a zooming car may have measured it to be x long but when it zooms past you, it appears to be shorter. IF the peer out their window, it appears as if you are moving and so you contract from their view. Principle of Equivalence: in any small region of space-time, the effects of a gravitational field are indistinguishable from those of an appropriate acceleration of the frame of reference. SPECIAL RELATIVITY: This tells us that because light always travels at the same speed, time dilates and length contracts to compensate for it. Gravity Bends Light: A gravitational lens is a distribution of matter (such as a cluster of galaxies) between a distant light source and an observer, that is capable of bending the light from the source as the light travels towards the observer.

Postulates of Special Relativity, Time Dilation, Twin Paradox, Simultaneity,

Postulates of Special Relativity: The first postulate of special relativity is the idea that the laws of physics are the same and can be stated in their simplest form in all inertial frames of reference.The second postulate of special relativity is the idea that the speed of light c is a constant, independent of the relative motion of the source. TIME DILATION: This occurs when another reference frame is moving relative to you, the observer. Time in that reference frame slows down relative to the time you measure. a slowing of time in accordance with the theory of relativity that occurs in a system in motion relative to an outside observer and that becomes apparent especially as the speed of the system approaches that of light. The moving mirror experiment, keep in mind that the reference frame must be moving really bloody fast for you to even see the effect. TWIN PARADOX: a thought experiment in special relativity involving identical twins, one of whom makes a journey into space in a high-speed rocket and returns home to find that the twin who remained on Earth has aged more. Simultaneity: something that appears to be simultaneous for you might not be simultaneous to the person you are observing. the concept that distant simultaneity - whether two spatially separated events occur at the same time - is not absolute, but depends on the observer's reference frame.

Quantization, Photoelectric Effect, Wave-Particle Duality, Double-Slit, Uncertainty Principle

Quantization: to subdivide (something, such as energy) into small but measurable increments. Everything is quantitized. Everything can be divided into smaller and smaller fundamental unit until it can no longer be divided. Photoelectric Effect: The emission of electrons from a metal when light shines on the metal Certain metal plate has light shone on it an electron bounces off and it can be detected by a positive wire or plate. A lights ability to eject an electron is solely based on its frequency and not its intensity. So if the beam of light was below a certain frequency and you shined the biggest bloody light on that plate, no electrons would bounce off. If the beam of light was above a certain frequency then a light less intense than light up sketches could eject an electron. a light is made up of quanta or photons which are particles of light. an electron is ejected when it is hit by a singular photon. Higher frequency means higher energy photons. light obeys wave particle duality. Wave-Particle Duality: the concept that all matter and energy exhibit both wave-like and particle-like properties. light and matter act light waves and particles. Double-Slit: a demonstration that light and matter can display characteristics of both classically defined waves and particles; moreover, it displays the fundamentally probabilistic nature of quantum mechanical phenomena. Electron beam is shot at slits with certain aperture openings. The electrons then exhibit diffraction and interference patterns just like light. Nuetrons also act like particles and waves. and object must pass an apture the size of its own wave length. Uncertainty Principle: the idea put forth by Werner Heisenberg in 1927 that the behavior of subatomic particles is uncertain, suggesting that all of the physical laws governing the universe are based on uncertainty

GRavity

SR and GR: special relativity and general relativity. What differentiates them. What are the two postulates of special relativity? The first one is if you have a reference frame of inertia(inertia reference frame) then all laws of nature are valid. The inertia reference frame is a reference frame that follows Newton's first law, the law of inertia. The reference frame can either be at rest or at constant velocity but it cannot be accelerating. Special relativity applies to all physical phenomena in the absence of gravity. General relativity explains the law of gravitation and its relation to other forces of nature. The second postulate is, the speed of light is a constant in a vacuum in all IRF. nothing is faster than the speed of light. EQUIVALENCY: Equivalence principle, fundamental law of physics that states that gravitational and inertial forces are of a similar nature and often indistinguishable. you can make gravity by having an accelerating reference frame. IN GENEral relativity, acceleration works. GRAVItY bends light: if you shine a light and move up at a fast rate, it bends the bloody light. GRAVITY SLOWS clock: GRAVITY and ACCELERATION equivalence:

x-ray and radio activity and transmutation and environmental radiation and unit of radiation and strong force and half life and carbon dating

X-RAY: very dangerous, harmful for living beings. Lead is so dense that the xray cannot penetrate it. The nuetron in the nucleus is like a strong binding force that helps keep the nucleas together, the strong force. if an atom starts to emit things out of it, it means it starts to decay. Alpha, beta (electron) and gamma ray (photon) Alpha has low energy moving towards gamma has more energy. Alpha radiation is the name for the emission of an alpha particle in fact an helium nuclei, beta radiation is the emission of electrons or positrons , and gamma radiation is the term used for the emission of energetic photons. Unlike alpha and beta particles, which have both energy and mass, gamma rays are pure energy. Gamma rays are similar to visible light, but have much higher energy. Gamma rays are often emitted along with alpha or beta particles during radioactive decay. RAD: REM: The difference between the rad and rem is that the rad is a measurement of the radiation absorbed by the material or tissue. The rem is a measurement of the biological effect of that absorbed radiation. For general purposes, most physicists agree that the Roentgen, Rad, and Rem may be considered equivalent. SIEVert: measures the energy absorbed in a humans body per unit of mass j/kg

Radioactivity

the process by which the nucleus of an atom of an element releases energy and particles. RADIOACTIVITY: the particles which are emitted from nuclei as a result of nuclear instability. Because the nucleus experiences the intense conflict between the two strongest forces in nature, it should not be surprising that there are many nuclear isotopes which are unstable and emit some kind of radiation. It is a byproduct of an unstable atom that spontaneously decays into other atoms and emitting radiation in the process. emission of radiation by a substance. electromagnetic radiation or nuclear radiation. nuclear radiation is when subatomic particles are emited from the nuclear of an atom. This is also called ionizing radiation because it is strong enough to knock of electrons off of elements. ALPHA radiation: atomic nuclear shoots out alpha particle. The alpha particle is in fact helium which has two protons and two nuetrons. BETA radiation: the nucleus shoots out an electron. This usually occurs when a nuetron turns into a proton and electron. The proton stays while the electron is the thing that is shoot out or escapes. GAMA radiation: this is when an extremely high radiation photon escapes the nucleas. This can damage surrounding materials. HALF LIFE: legit the half life of something dawg. A decaying element, once it decays bloody half of its original magnitude, that's the bloody half life. RAYS: an idealized model of light, obtained by choosing a line that is perpendicular to the wavefronts of the actual light, and that points in the direction of energy flow. A ray is a beam of light or radiation. Even on cloudy days, you sometimes see a ray of sunlight shine through the clouds. In physics, a ray is a line or column of light, heat, or electromagnetic radiation (like an x-ray)