Essential Physics Definitions: Electricity, Nuclear, and Waves

Essential Physics Definitions

Electricity and Circuits

• Grounding: Removing an excess charge by connecting an object to Earth.
• Lightning: The discharge of negative electrons at the bottom of thunderclouds to Earth's surface through ionized air.
• Electric Field: The area around an electric charge in which it shows its effect (attraction or repulsion).
• Positive Charge: Lines coming out from the charge.
• Negative Charge: Lines going into the charge.
• Electric Current: The flow of charged particles.
• Electric Power (Watts): The rate at which electric energy is transformed (e.g., a hair dryer).
• Power: The rate at which energy is transformed.
• Voltage: A source of potential difference that is less than the potential difference across the load (or battery terminals).
• Conventional Current: The direction in which positive charge moves.
• Battery: Several galvanic cells connected together.
• Parallel Connection: A circuit where the current has two or more paths to follow.
• Series Connection: A connection with only one current path.

Nuclear Physics Concepts

• Fission: The division of a nucleus into two or more fragments.
• Fusion: Nuclei with small masses combine to form a nucleus with a larger mass.
• Strong Nuclear Force: An attractive force between nucleons that are held closely together, as they are in a nucleus.
• Isotopes: The puzzle of atomic masses that are not whole numbers can be solved by applying electromagnetism. All isotopes of a neutral element have the same number of electrons as protons and behave chemically in the same way.
• Nuclear Reaction: The number of electrons and protons in the nucleus changes.
• Alpha Decay: The emission of an alpha particle from nucleons.
• Beta Decay: A decay process in which a neutron is changed to a proton or a proton to a neutron within the nucleus.
• Gamma Decay: A decay process in which there is a redistribution of energy within the nucleus but no change in atomic mass.
• Biological Effects of Nuclear Radiation: Acute radiation sickness and burns are less severe than at higher exposure doses.

Waves and Optics

Wave Types

• Types of Waves: Mechanical waves and electromagnetic waves.
• Mechanical Waves: Need matter to transfer energy.
• Electromagnetic Waves: Do not need matter to transfer energy. They can travel through matter, such as air, water, and glass.
• Matter: The substance through which a wave can travel (e.g., air, water, solids, liquids).

Reflection and Thermal Concepts

• Reflection: Bouncing off a surface.
• Regular Reflection: Rays of light hit a smooth surface, and the rays are reflected back at the same angle.
• Diffuse Reflection: Rays of light hit a bumpy surface, which causes the rays to bounce back at different angles.
• Thermal Equilibrium: The state in which the rates of thermal energy transfer between two objects are equal, and the objects are at the same temperature.