The whole of AQA GCSE Combined Science Physics Paper 1 in under 60 minutes - Thursday 22nd May 2025

Important exam advice includes writing in black pen within the answer box, using SI units for calculations (and converting when necessary), answering extended response questions in bullet points, and providing justified conclusions for 'evaluate' questions. Methods should be logical, numbered lists. Working scientifically skills such as identifying variables, understanding repeatability vs. reproducibility, resolution of equipment, and interpreting graphs (including curved lines of best fit) are also covered. The video discusses systematic and random errors, emphasizing the importance of multiple readings for calculating a mean.

Mathematical skills constitute a significant portion of science papers (20%) and physics papers (30%). The video highlights the importance of knowing unit prefixes (milli, micro, nano, kilo, mega, giga) which are mostly factors of 1000, with the exception of centimeters. Students will receive a physics equation sheet, but must know how to rearrange equations and identify units. Essential units for energy, mass, speed, height, gravitational field strength, temperature, specific heat capacity, time, power, charge, current, potential difference, and resistance are reviewed.

A system stores energy in various forms: magnetic, kinetic, thermal, gravitational potential, chemical, elastic potential, electrostatic, and nuclear. Energy can be transferred by heating, mechanically, electrically, and by radiation. The principle of conservation of energy states that energy cannot be created or destroyed within a closed system, only transferred between stores. All energy is measured in Joules. The video provides examples of calculating gravitational potential energy, kinetic energy, and elastic potential energy, emphasizing unit consistency (e.g., height in meters, mass in kilograms, extension in meters) and the ability to rearrange formulas.

Specific heat capacity is the energy required to raise the temperature of 1 kg of a substance by 1°C. The formula ΔE = m c Δθ (change in energy = mass x specific heat capacity x change in temperature) is explained, with a focus on understanding the 'delta' symbol for change. The required practical for determining specific heat capacity involves a metal block or liquid, a balance, insulation, a thermometer, an electrical heater, and equipment to measure potential difference, current, and time (or a joulemeter) to calculate energy transferred. The importance of minimizing heat loss and accurate temperature measurement is stressed.

Power is defined as the rate at which energy is transferred or work is done, measured in Watts (Joules per second). The more powerful an appliance, the faster it transfers energy. Efficiency is the proportion of usefully transferred energy, expressed as a decimal or percentage. Energy conservation dictates that total energy remains constant, but some is wasted (often as heat, which dissipates). Methods to reduce wasted energy include insulation (considering thermal conductivity), streamlining to reduce drag, and reducing friction (using wheels or lubrication).

Energy resources are categorized as renewable (generated faster than used) or non-renewable (used faster than generated). Students should be able to discuss the advantages and disadvantages of various resources for transport, heating, and electricity generation, considering factors like renewability, cost, carbon emissions, reliability, geographic restrictions, and waste disposal (for nuclear power).

Knowledge of circuit symbols and their correct usage in diagrams (using a ruler, no gaps) is essential. Common pitfalls like drawing a resistor with a line through it, making it a fuse, are highlighted. Various electrical equations are discussed, emphasizing the need to know units to identify quantities and the possibility of multi-step calculations. Current is the flow of charge, and potential difference is the energy transferred by a component. The historical concept of 'conventional current' is explained.

Required practical 15 involves measuring current (I) and potential difference (V) for wires of different lengths and for resistors in series and parallel to determine resistance (R = V/I). Practical 16 extends this to various circuit components. Key circuit setup rules include placing the ammeter in series and the voltmeter in parallel. The video illustrates typical IV graphs for ohmic conductors (linear), filament lamps (S-shaped due to resistance increasing with temperature), and diodes (current flows in one direction only, with a small threshold voltage).

Light-dependent resistors (LDRs) and thermistors show varying resistance with light intensity and temperature, respectively (e.g., LDR resistance decreases with brighter light, thermistor resistance decreases with higher temperature). The video then distinguishes between series and parallel circuits, explaining how current behaves (same everywhere in series, splits in parallel) and how potential difference behaves (splits in series, same across branches in parallel). Total resistance calculations for both circuit types are also covered.

British mains electricity uses alternating current (AC) at 50 Hz and approximately 230 volts. Direct current (DC) flows in one direction (e.g., from batteries). Three-core cables and three-pin plugs are explained: the outer casing is insulating plastic, the pins are brass (a hard alloy), and the three wires (Live/brown, Neutral/blue, Earth/green and yellow) have specific functions and positions for safety. Fuses, which melt to break the circuit if current is too high, are also a crucial safety feature, and choosing the appropriate fuse is discussed.

The National Grid is a network of cables and transformers connecting power stations to consumers. Transformers are crucial for efficient power transmission: step-up transformers increase potential difference for long-distance cables to reduce energy loss as heat (due to lower current), and step-down transformers then reduce it to a safe level for consumers.

The three states of matter (solid, liquid, gas) are described by particle arrangement (regular in solids, close but random in liquids, widely spaced in gases), inter-particle forces (strongest in solids, weakest in gases), and particle movement (vibration in solids, sliding in liquids, random motion in gases). This explains properties like compressibility. State changes (melting, freezing, boiling, evaporating, condensing, sublimating) are physical changes where mass is conserved, but specific terms like boiling (bulk process at boiling point) and evaporation (surface phenomenon at lower temperatures) are differentiated.

Density (mass/volume) measures how much mass is in a given volume, affected by particle spacing. The required practical for determining density involves measuring mass with a balance and volume using various methods: measuring cylinder for liquids, ruler/calipers for regular solids, and displacement (Eureka can) for irregular solids. The principle of displacement is explained: the volume of water displaced equals the volume of the object.

Internal energy is the total kinetic and potential energy of particles in a system. When heating a substance, its internal energy increases; this can lead to a temperature rise (increased kinetic energy) or a change of state (increased potential energy). The heating curve of ice to steam illustrates that during state changes (melting, boiling), temperature remains constant. Specific latent heat is the energy required to change the state of 1 kg of a substance, with specific latent heat of fusion for melting and vaporization for boiling.

Molecules of a gas are in constant random motion; higher temperature means higher average kinetic energy. At a constant temperature, pressure and volume are inversely proportional (Boyle's Law). However, in real-world scenarios, decreasing a gas's volume typically increases its temperature.

The nuclear model of the atom has a small, dense nucleus (protons and neutrons) orbited by electrons in shells. Relative masses and charges of protons (+1, mass 1), neutrons (0, mass 1), and electrons (-1, very small mass) are reviewed. Atomic number (bottom number) indicates protons and electrons; mass number (top number) indicates protons + neutrons. The radius of an atom is about 0.1 nm, with the nucleus being much smaller (1/10,000th of the atomic radius). Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons.

The model of the atom evolved through scientific discovery: John Dalton (solid, indivisible spheres), J.J. Thomson (plum pudding model with electrons in a positive sphere), Ernest Rutherford (alpha scattering experiment revealing a small, dense, positively charged nucleus and mostly empty space), Niels Bohr (electrons orbit at fixed distances/shells), and James Chadwick (discovery of neutrons).

Unstable atomic nuclei undergo random radioactive decay, emitting radiation (alpha, beta, gamma) to become more stable. Activity (rate of decay) is measured in Becquerels (Bq) using a Geiger-Müller tube. All radiation types ionize other atoms by removing electrons. Alpha particles (2 protons, 2 neutrons) are highly ionizing but not very penetrating, stopped by paper. Beta particles (fast-moving electrons) are less ionizing and more penetrating, stopped by thin aluminum. Gamma rays (electromagnetic waves) are the least ionizing and most penetrating, requiring thick lead for shielding. Nuclear equations for alpha and beta decay are explained, focusing on balancing mass and atomic numbers.

Half-life is the time taken for the activity or number of radioactive nuclei in a sample to halve. This can be determined from graphs or given data, emphasizing counting the number of 'halvings' (arrows) rather than the number of values. Finally, the hazards of radioactive contamination (unwanted radioactive atoms on an object, posing a risk through their decay) and irradiation (exposure to radiation, but not becoming radioactive oneself) are differentiated. Irradiation can cause DNA damage but ceases when the source is removed; it is used in sterilization.