Glossary
Alpha Particles (α)
A type of radiation consisting of a helium nucleus (two protons and two neutrons), which is relatively heavy and has low penetrating power.
Example:
A sheet of paper or even human skin can easily block alpha particles due to their large size and charge.
Atomic Physics
The field of physics concerned with the structure of atoms, their energy states, and their interactions with other particles and fields.
Example:
Studying the specific colors of light emitted by a neon sign involves the principles of atomic physics and electron energy transitions.
Beta Particles (β)
A type of radiation consisting of high-speed electrons or positrons, which are lighter and more penetrating than alpha particles.
Example:
While beta particles can be stopped by a thin sheet of aluminum, they are more penetrating than alpha particles and can cause skin burns.
Double-Slit Experiment
A classic experiment demonstrating wave-particle duality, where particles (like electrons) passing through two slits create an interference pattern, characteristic of waves.
Example:
The double-slit experiment famously showed that even individual electrons behave like waves, creating an interference pattern on a screen.
Electromagnetic Force
One of the four fundamental forces, it acts between electrically charged particles and is responsible for phenomena like electricity, magnetism, and chemical bonds.
Example:
The electromagnetic force holds atoms together by attracting negatively charged electrons to the positively charged nucleus.
Frequency (f)
The number of cycles or oscillations of a wave that pass a given point per unit of time.
Example:
High-pitched sounds have a higher frequency than low-pitched sounds, corresponding to more sound wave cycles per second.
Gamma Rays (γ)
A type of high-energy electromagnetic radiation (photons) emitted during radioactive decay, possessing the highest penetrating power.
Example:
Thick lead or concrete shielding is often required to protect against highly penetrating gamma rays emitted from nuclear reactions.
Gravitational Force
One of the four fundamental forces, it is the attractive force between any two objects with mass, acting over long distances but being the weakest of the four.
Example:
The gravitational force is what keeps the Moon in orbit around the Earth and causes objects to fall towards the ground.
Half-Life
The time it takes for half of the radioactive nuclei in a given sample to undergo radioactive decay.
Example:
If a radioactive isotope has a half-life of 10 days, then after 20 days (two half-lives), only one-quarter of the original sample will remain.
Mass Defect
The difference between the mass of an atomic nucleus and the sum of the masses of its individual constituent protons and neutrons.
Example:
The mass defect in a helium nucleus accounts for the binding energy that holds its nucleons together, released when the nucleus forms.
Mass-Energy Equivalence (E=mc²)
Einstein's principle stating that mass and energy are interchangeable and can be converted into one another, with 'c' being the speed of light.
Example:
In nuclear fusion, a tiny amount of mass is converted into a tremendous amount of energy, as famously described by E=mc².
Momentum (p)
A measure of the quantity of motion of a particle, calculated as the product of its mass and velocity.
Example:
A fast-moving electron has greater momentum than a slow-moving one, even if they have the same mass.
Nuclear Physics
The branch of physics that studies the atomic nucleus, its constituents (protons and neutrons), and the forces and reactions that govern its behavior.
Example:
Investigating the stability of different isotopes and the processes of radioactive decay falls under the domain of nuclear physics.
Nuclear Reactions (Fusion/Fission)
Processes involving changes in the atomic nucleus, where nuclei either combine (fusion) or split apart (fission), releasing significant amounts of energy.
Example:
The Sun generates its immense energy through nuclear fusion of hydrogen into helium, while nuclear power plants use controlled nuclear fission.
Photoelectric Effect
The phenomenon where electrons are emitted from a metal surface when light shines on it, provided the light's frequency is above a certain threshold.
Example:
Solar panels convert sunlight into electricity by utilizing the photoelectric effect, where photons knock electrons free from a semiconductor material.
Photon Energy (E = hf)
The energy carried by a single photon, which is directly proportional to its frequency (f), with 'h' being Planck's constant.
Example:
Blue light has a higher photon energy than red light because blue light has a higher frequency.
Photons
Discrete packets or quanta of light energy, which are the fundamental particles of electromagnetic radiation.
Example:
When an atom emits light, it releases tiny, indivisible packets of energy called photons.
Probability (in Quantum Mechanics)
In quantum mechanics, the likelihood of finding a particle at a particular location or in a specific state, determined by the square of its wave function.
Example:
Due to probability in quantum mechanics, we can only predict the likelihood of an electron being in a certain region, not its exact position at any given moment.
Quantum Physics
The branch of physics that studies matter and energy at the most fundamental level, focusing on the behavior of particles at atomic and subatomic scales.
Example:
Understanding how a laser works, where light is emitted in discrete packets, requires the principles of quantum physics.
Radioactive Decay
The process by which an unstable atomic nucleus loses energy by emitting radiation, transforming into a more stable nucleus.
Example:
Carbon-14 undergoes radioactive decay to become Nitrogen-14, a process used in carbon dating to determine the age of ancient artifacts.
Strong Nuclear Force
One of the four fundamental forces, it is the strongest force and acts over extremely short distances to bind protons and neutrons together within the atomic nucleus.
Example:
Despite the electrostatic repulsion between protons, the strong nuclear force is powerful enough to hold them tightly within the nucleus.
System (in Quantum Physics)
In quantum physics, a 'system' refers to the specific collection of interacting particles and energy that is being observed or analyzed.
Example:
An electron orbiting a proton in a hydrogen atom can be considered a simple system in quantum mechanics.
Threshold Frequency
The minimum frequency of incident light required to eject electrons from a particular metal surface in the photoelectric effect.
Example:
If the light shining on a metal is below its threshold frequency, no electrons will be emitted, regardless of the light's intensity.
Wave Functions (Ψ)
Mathematical functions in quantum mechanics that describe the quantum state of a particle, containing all possible information about its properties.
Example:
The wave function for an electron in an atom allows physicists to calculate the probability of finding the electron at various locations around the nucleus.
Wave-Particle Duality
The concept in quantum mechanics that particles can exhibit properties of both waves and particles, and waves can exhibit properties of particles.
Example:
Light demonstrates wave-particle duality, acting as a wave when it diffracts through a prism and as particles (photons) in the photoelectric effect.
Wavelength (λ)
The spatial period of a periodic wave, which is the distance over which the wave's shape repeats.
Example:
Red light has a longer wavelength than blue light, which is why it bends less when passing through a prism.
Weak Nuclear Force
One of the four fundamental forces, it is responsible for certain types of radioactive decay, such as beta decay, where particles change their identity.
Example:
The weak nuclear force allows a neutron to transform into a proton, an electron, and an antineutrino during beta decay.
Work Function
The minimum amount of energy required to remove an electron from the surface of a specific metal.
Example:
Different metals have different work functions; for instance, it takes more energy to remove an electron from platinum than from cesium.