Energy and the Law of Conservation

Energy and the Law of Conservation

• Energy represents the capacity to perform work or induce change, quantified in joules (J).
• The Law of Conservation of Energy states energy is neither created nor destroyed, but only transformed.
• Kinetic energy is energy of motion, manifesting as heat, light, sound, electrical, and mechanical forms.
• Potential energy is stored, appearing as chemical, nuclear, gravitational, and elastic forms.
• Energy transformation involves changing one type of energy into another.
• Energy efficiency measures how much of the initial energy is converted into useful energy.
• Efficiency (%) is calculated as (Useful Energy ÷ Initial Energy) × 100.
• Sankey Diagrams represent energy amounts using the thickness of arrows, with useful energy progressing forward and wasted energy going down.

Energy Sources & Electricity Generation

• Renewable energy is derived from naturally replenishing sources like solar, wind, hydro, geothermal, and biomass.
• Renewable energy offers sustainability, low environmental impact, and no fuel costs.
• Renewable energy is expensive to install and dependent on location and weather conditions.
• Non-renewable energy, such as from coal, oil, natural gas, and nuclear sources, cannot be replenished quickly.
• Non-renewable energy is reliable, with consistent energy output.
• Non-renewable energy pollutes the environment and draws on finite resources.
• Electricity generation requires power plants to convert energy into electricity using turbines and generators.
• An example of energy transformation in power plants includes converting coal to heat, then to kinetic energy, and finally to electrical energy.
• Non-renewable sources have a higher environmental footprint, releasing greenhouse gases and pollutants, unlike renewable sources.

Electrical Energy & Circuits

• Electrical circuits provide a path for electricity to flow, with electric charges moving through conductors and gaining energy from a power source.
• A power source (e.g., battery) provides energy to a circuit.
• Conductors (e.g., wires) allow electricity to flow.
• A load (e.g., lightbulb) converts electrical energy into other forms.
• A switch opens or closes a circuit.
• Current is the flow of electric charge, measured in amperes (A).
• Direct Current (DC) flows in one direction and often powers battery-operated devices.
• Alternating Current (AC) flows in multiple directions and are used with household electricity.
• Voltage (V) is the force pushing electric charge through a circuit, measured in volts (V).
• Resistance (R) measures an object's opposition to the flow of electricity, measured in ohms (Ω).
• Ohm’s Law describes the relationship between voltage, current, and resistance.
• The formula for Ohm's Law is V = I × R, where V = Voltage (volts), I = Current (amps) and R = Resistance (ohms).
• If resistance increases, current decreases within a circuit.
• If voltage increases, current increases within a circuit.

Series and Parallel Circuits

• Series circuits arrange all components along a single path.
• Current remains constant throughout a series circuit.
• Voltage is divided across components in a series circuit.
• If one component fails in a series circuit, the entire circuit breaks.
• Parallel circuits arrange components along multiple paths.
• Current is divided across branches in a parallel circuit.
• Voltage remains constant across each branch in a parallel circuit.
• If one component fails in a parallel circuit, the others continue to function.

Resistance in Electrical Circuits

• Factors affecting resistance include: wire length, wire thickness, material, and temperature.
• Longer wires offer more resistance.
• Thicker wires offer less resistance.
• Materials like copper have low resistance, while materials like nichrome have high resistance.
• Higher temperatures increase resistance.
• Resistance and heat: Electrons encounter resistance when flowing through a conductor, generating heat.
• High resistance materials (e.g., nichrome) are used for heating elements in devices like toasters and electric irons.

Energy Efficiency and Energy Flow

• Energy flow refers to the transfer of energy into or out of a system.
• In closed systems, the total energy remains constant.
• In open systems, energy can flow in and out, causing a change in total energy.
• Sankey diagrams are employed to visualize energy transformations and waste.
• In Sankey diagrams, thicker arrows represent more energy, while wasted energy is indicated by a downward arrow.

Types of Energy

• Kinetic energy is the energy of motion.
• Potential energy is stored energy.
• Mechanical energy consists of the sum of kinetic and potential energy in a system.
• Thermal (heat) energy relates to the temperature of an object or system.
• Chemical energy is stored in the bonds of atoms & molecules.
• Electrical energy derives from the flow of electric charge.
• Nuclear energy resides in the nucleus of atoms.
• Radiant energy is carried by electromagnetic waves, including light.