Energy Storage and Changes

Ever wondered how a roller coaster works or why your phone battery runs out? It's all about energy changes in systems. A system can be anything from a single object to a whole group of things working together.

You'll need to master several key equations here. Kinetic energy $Ek = ½mv²$ tells you how much energy something has when it's moving. Gravitational potential energy $Ep = mgh$ shows the energy stored when you lift something up. Don't forget elastic potential energy in springs and the thermal energy equation for temperature changes.

Specific heat capacity is crucial - it's how much energy you need to heat 1kg of a material by 1°C. You'll investigate this in your first required practical, so make sure you understand the method and can calculate results confidently.

Quick Tip: Energy is never created or destroyed, just moved around - this principle will help you solve most energy problems!

Power and Energy Efficiency

Power is simply how fast energy gets transferred - measured in watts $1 watt = 1 joule per second$. Two machines might use the same total energy, but the one that does it faster has more power.

The big idea here is conservation of energy - energy never disappears, but it often gets "wasted" as heat or sound. Think about your laptop getting warm or a car engine making noise. Efficiency calculations show you what percentage of energy actually does useful work.

Thermal conductivity affects how quickly heat escapes from buildings. Thicker walls with better insulation mean less energy waste. Your second required practical tests different insulating materials - perfect exam material.

Energy resources split into renewable (wind, solar, hydro) and non-renewable (fossil fuels, nuclear). Each has advantages and disadvantages you'll need to evaluate, considering environmental impact, reliability, and cost.

Exam Focus: Efficiency questions are common - remember it's useful energy out divided by total energy in, often expressed as a percentage.

Electrical Circuits and Safety

Electric current is the flow of charge around a circuit - no complete circuit means no current. The key equation V = IR (Ohm's law) links potential difference, current, and resistance together.

Different components behave differently. Ohmic conductors follow Ohm's law perfectly, but lamps, diodes, and thermistors have curved I-V graphs. LDRs $light-dependent resistors$ change resistance with light levels. Your practicals will involve investigating these characteristics.

Series circuits have the same current everywhere but split the voltage. Parallel circuits have the same voltage across each branch but split the current. Adding resistors in series increases total resistance; adding them in parallel decreases it.

Mains electricity safety is vital knowledge. The live wire (230V) is dangerous even when switches are off. The neutral wire and earth wire protect us from electrocution. Understanding three-pin plugs could literally save your life.

Safety First: Never assume a circuit is safe just because it's switched off - the live wire can still be at 230V!

Atomic Structure and Radioactivity

Atoms contain protons, neutrons, and electrons, but our understanding has evolved through experiments. Isotopes have the same number of protons but different numbers of neutrons, affecting their stability.

Radioactive decay produces alpha particles, beta particles, and gamma rays, each with different penetrating power and ionising ability. Alpha is stopped by paper, beta by aluminium, and gamma needs thick lead. This affects their uses and dangers.

Half-life is the time for half the radioactive nuclei to decay. This concept helps predict how dangerous radioactive materials will be over time. You'll need to balance nuclear equations and calculate activity in Becquerels.

Nuclear fission splits heavy nuclei and can create chain reactions in power stations. Nuclear fusion joins light nuclei together - it powers the sun but is incredibly difficult to control on Earth. Both processes release enormous amounts of energy compared to chemical reactions.

Remember: Background radiation is everywhere - from space, rocks, and human activities. It's completely natural and usually harmless at low levels.