Energy Concepts and Transfers

Types of Energy:
- Kinetic energy: energy of motion
- Potential energy: stored energy
- Thermal energy: energy of heat
- Electrical energy: energy of moving charges
- Chemical energy: energy stored in chemical bonds
- Nuclear energy: energy stored in atomic nuclei
Energy Transfers:
- Energy cannot be created or destroyed, only transferred from one form to another
- Energy transfers can occur through work, heat, or radiation
Energy Efficiency:
- Efficiency = (useful energy output / total energy input) x 100%
- No energy transfer is 100% efficient due to energy losses

Types of Radiation:
- Alpha (α) particles: high-energy helium nuclei, stopped by paper or skin
- Beta (β) particles: high-energy electrons, stopped by aluminum or thick paper
- Gamma (γ) radiation: high-energy electromagnetic waves, stopped by lead or thick concrete
Radioactive Decay:
- Unstable nuclei emit radiation to become more stable
- Half-life: time taken for half of the radioactive substance to decay
Uses of Radioactivity:
- Medical applications: cancer treatment, imaging, and diagnosis
- Industrial applications: food irradiation, sterilization, and dating

Electric Charge:
- Positive charge: protons
- Negative charge: electrons
Electric Current:
- Flow of electrons from negative to positive terminal
- Measured in amperes (A)
Resistance:
- Opposition to electric current
- Measured in ohms (Ω)
- Depends on conductor material, length, and temperature
Circuit Components:
- Resistors: control voltage or current
- Capacitors: store electric energy
- Diodes: allow current to flow in one direction

Types of Waves:
- Mechanical waves: require a medium, e.g., water waves, sound waves
- Electromagnetic waves: do not require a medium, e.g., light, radio waves
Wave Properties:
- Amplitude: maximum displacement from equilibrium
- Frequency: number of oscillations per second
- Wavelength: distance between consecutive oscillations
- Speed: distance traveled per second
Wave Behavior:
- Reflection: wave bounces back from a surface
- Refraction: wave changes direction when passing through a medium
- Diffraction: wave bends around an obstacle or through a narrow opening

Types of Energy:
- Kinetic energy is the energy of motion
- Potential energy is stored energy, e.g., gravitational, elastic, or electrical
- Thermal energy is the energy of heat, resulting from the motion of particles
- Electrical energy is the energy of moving charges, e.g., electrons
- Chemical energy is stored in chemical bonds, e.g., food, batteries
- Nuclear energy is stored in atomic nuclei, e.g., nuclear reactors
Energy Transfers:
- Energy is conserved, meaning it cannot be created or destroyed, only transferred
- Energy transfers occur through work, heat, or radiation
- Energy can be converted from one form to another, but some energy is lost as heat
Energy Efficiency:
- Efficiency is calculated as (useful energy output / total energy input) x 100%
- No energy transfer is 100% efficient due to energy losses, such as heat or friction

Types of Radiation:
- Alpha (α) particles are high-energy helium nuclei, stopped by paper or skin
- Beta (β) particles are high-energy electrons, stopped by aluminum or thick paper
- Gamma (γ) radiation is high-energy electromagnetic waves, stopped by lead or thick concrete
Radioactive Decay:
- Unstable nuclei emit radiation to become more stable, a process called radioactive decay
- Half-life is the time taken for half of the radioactive substance to decay
- Radioactive decay is a random process, and it's impossible to predict when a specific nucleus will decay
Uses of Radioactivity:
- Medical applications: cancer treatment, imaging, and diagnosis, e.g., PET scans
- Industrial applications: food irradiation, sterilization, and dating, e.g., carbon dating

Electric Charge:
- Positive charge is associated with protons, found in the nucleus of an atom
- Negative charge is associated with electrons, found orbiting the nucleus
Electric Current:
- Electric current is the flow of electrons from negative to positive terminal
- Current is measured in amperes (A), with 1 A = 1 Coulomb per second
Resistance:
- Resistance is the opposition to electric current, measured in ohms (Ω)
- Resistance depends on the conductor material, length, and temperature
- Increasing the length or temperature of a conductor increases its resistance
Circuit Components:
- Resistors control voltage or current, and are used to divide voltage or limit current
- Capacitors store electric energy, and are used to filter or regulate voltage
- Diodes allow current to flow in one direction, and are used to rectify alternating current (AC)

Types of Waves:
- Mechanical waves require a medium, such as water or air, to propagate
- Electromagnetic waves do not require a medium, and can propagate through a vacuum
Wave Properties:
- Amplitude is the maximum displacement from equilibrium, and is measured in meters
- Frequency is the number of oscillations per second, and is measured in hertz (Hz)
- Wavelength is the distance between consecutive oscillations, and is measured in meters
- Speed is the distance traveled per second, and is measured in meters per second (m/s)
Wave Behavior:
- Reflection occurs when a wave bounces back from a surface, e.g., echo or mirror reflection
- Refraction occurs when a wave changes direction when passing through a medium, e.g., light through a prism
- Diffraction occurs when a wave bends around an obstacle or through a narrow opening, e.g., sound around a corner