Physics Paper 1 Comprehensive Revision Notes

Physics Paper 1 Revision Foundations and Check-In Activity

Vector vs. Scalar Quantities: A vector quantity has both magnitude and a specific direction, whereas a scalar quantity has magnitude only and does not have a direction.
Momentum Relationships: The link between momentum ( $p$ ), mass ( $m$ ), and velocity ( $v$ ) is defined by the equation: $p = m \times v$
Energy Stores in Specific Contexts:
- Hot Object: The primary energy store is thermal energy.
- Food and Batteries: The primary energy store is chemical energy.
Circuit Resistance and Current: In a circuit, as the resistance increases, the current decreases.
Balanced Forces: If the forces acting on a moving object are balanced, the object keeps moving at a constant velocity.
Relative Formula Mass ( $M_r$ ):
- For water ( $H_2O$ ): $M_r = 1 + 1 + 16 = 18$
Molar Mass of Carbon: The atomic weight of carbon is approximately $12$ . Therefore, $1\,mole$ of carbon weighs $12\,g$ .
Revision Date Reference: Friday, 12th of June, 2026.

Chemical and Atomic Structure Fundamentals

Electron Shell Configuration: Electrons occupy energy shells in the pattern of $2, 8, 8$ for the first, second, and third shells respectively.
Bonding Definitions:
- Ionic Bonding: Electrons are transferred from metal atoms to non-metal atoms.
- Covalent Bonding: Electrons are shared in pairs between atoms to achieve stable electronic configurations.
- Metallic Bonding: Metals lose outer shell electrons to become positive ions; these electrons become delocalised throughout the structure.
Ionic Compounds Example ( $NaCl$ ):
- Sodium ( $Na$ ) transfers one electron to Chlorine ( $Cl$ ).
- The resulting ions are $Na^+$ and $Cl^-$ .
Achieving Full Shells: Lithium can achieve a full outer shell by losing its single outer electron.
Electrolysis Terminology:
- Anode: The positive electrode ( $+$ ).
- Cathode: The negative electrode ( $–$ ).
Electrical Conductivity in Ionic Compounds: Ions are free to move and conduct electricity when the compound is in two states:
- Molten (liquid state).
- Aqueous solution (dissolved in water).

Exam Structure and Command Word Techniques

Physics Paper 1 Topic Areas and Weighting:
1. Circuits: $9\,marks$
2. Density: $13\,marks$
3. National Grid: $12\,marks$
4. Energy and Motion: $8\,marks$
5. Specific Heat Capacity: $10\,marks$
6. Resistance: $7\,marks$
7. Radioactivity: $11\,marks$
- Total Marks: $70\,marks$
Primary Physics 1 Themes: Energy; Electricity; Particle model of matter; Atomic structure.
Command Word Strategies:
- Explain: Provide a reason for what is happening and why. Use connectives like "so that," "because," or "this means that."
- Describe a Method:
  - Identify variables: Independent, dependent, and control variables.
  - Provide a clear, numbered sequence of step-by-step instructions.
  - Ensure the procedure is replicable by a peer.
  - Explain the data recording process and the necessity of repeats.
- Similarities & Differences: Use comparative "-er" words (e.g., smaller, faster, larger) and stick strictly to observable scientific facts.
- Suggest: Apply personal knowledge to a novel or unfamiliar situation to make an educated guess.
- Calculate: Perform mathematical operations to find a numerical value.

Energy Stores and Calculations

Identified Energy Stores: Chemical, Gravity, Kinetic, Thermal, Elastic, Vibration, Nuclear, Electric, Magnetic.
Core Energy Formulas:
- Kinetic Energy: $E_k = 0.5 \times m \times v^2$
- Elastic Potential Energy: $E_e = 0.5 \times k \times e^2$
- Gravitational Potential Energy: $E_p = m \times g \times h$
- Thermal Energy Change: $\Delta E = m \times c \times \Delta\theta$
Calculating with Multiple Components: In scenarios involving multiple elastic cords (e.g., two cords), the calculated elastic potential energy for one cord must be multiplied by $2$ .
Conservation of Energy Principle: Energy is never created or destroyed. In theoretical problems (e.g., a pod moving between heights and springs), you can often assume $GPE = EPE$ .
Energy Dissipation in Real Situations: A pod or object will not reach its maximum theoretical height because work is done against air resistance and friction. This results in energy being dissipated as thermal energy to the surroundings.

Energy Resources and Efficiency

Resource Definitions:
- Renewable: Resources that are replenished as they are used (e.g., wind, solar, tides).
- Non-renewable: Resources that will eventually run out (e.g., fossil fuels, nuclear).
UK Energy Trends (2010–2020): The UK has quadrupled electricity generation from renewables while significantly decreasing fossil fuel usage.
Reliability and Environment:
- Renewables like solar and wind are weather-dependent (e.g., zero solar output at night).
- Wind turbines do not emit carbon dioxide ( $CO_2$ ) during operation, unlike coal-fired stations which contribute to climate change.
Efficiency and Lubrication:
- Oiling mechanical parts reduces friction between moving surfaces.
- Less work is done against friction, meaning less energy is dissipated as waste heat.
- A higher proportion of input energy is transferred to a useful store, increasing efficiency.

Internal Energy and Specific Heat Capacity

Components of Internal Energy:
1. Kinetic Energy Store: Relates to the speed of particles; increases as temperature increases.
2. Potential Energy Store: Relates to the state of matter; increases during a change of state while temperature remains constant.
Heating Graph Analysis:
- Solid/Liquid/Gas Phases: Temperature and internal energy increase; kinetic energy increases; potential energy remains constant.
- Melting/Boiling (Change of State): Temperature remains constant; internal energy increases; kinetic energy remains constant; potential energy increases.
Specific Heat Capacity (SHC): The energy required to raise the temperature of $1\,kg$ of a substance by $1\,^{\circ}C$ .
Specific Latent Heat (SLH): The energy required to change the state of $1\,kg$ of a substance while keeping the temperature constant.
Comparison on Graphs:
- A steeper gradient on a heating graph indicates a lower SHC because less energy is needed for a fixed temperature increase.
- A longer horizontal plateau indicates a higher SLH because more time (and thus energy) is needed to complete the state change.

Required Practical: Specific Heat Capacity

Apparatus Setup:
1. Place immersion heater in the central hole of the block.
2. Place thermometer in the smaller hole using water or oil to ensure thermal contact.
3. Insulate the block with suitable material to prevent heat loss.
Procedure:
1. Record initial temperature.
2. Turn on the power supply for ten minutes.
3. Record the highest temperature reached (temperature continues to rise slightly after the heater is switched off).
4. Calculate the temperature rise ( $\Delta\theta$ ).
Energy Measurement: Record energy from a joulemeter or calculate using: $\text{Energy} = V \times I \times t$
Novel Calculation Example:
- Water Mass: $5.0\,kg$
- $\Delta E$ (Change in thermal energy): $1260\,kJ$
- SHC of water: $4200\,J/kg\,^{\circ}C$
- Finding start temperature: If the final temp is $75\,^{\circ}C$ and the calculated change is $60\,^{\circ}C$ , the starting temperature is $15\,^{\circ}C$ .

Electricity: Current, Potential Difference, and Resistance

Potential Difference ( $V$ ): The energy transferred per unit charge passed. It is the "push" moving the charge.
- $1\,Volt = 1\,J/C$ .
Current ( $I$ ): The rate of flow of electrical charge (carried by electrons in metals).
- Unit: Amperes ( $A$ ).
Resistance ( $R$ ): A measure of opposition to current flow.
- Unit: Ohms ( $\Omega$ ).
Ohm's Law: For a fixed resistor at constant temperature, potential difference is directly proportional to current ( $V = I \times R$ ).

Circuit Components and Characteristics

Diode: Allows current in one direction only. It has very high resistance in the reverse direction. In the forward direction, resistance drops sharply at higher potential differences.
Thermistor: Resistance decreases as temperature increases.
- Mnemonic: TURD (Temperature Up, Resistance Down).
Light Dependent Resistor (LDR): Resistance decreases as light intensity increases.
- Mnemonic: LURD (Light Up, Resistance Down).
Filament Bulb: Resistance increases as potential difference increases. The filament temperature rises, causing ions to vibrate more, which obstructs the flow of electrons.

Electricity Practical: Resistance of a Wire

Method:
1. Connect the ammeter in series and the voltmeter in parallel.
2. Use a ruler to measure the length of wire between crocodile clips (e.g., $17.8\,cm$ ).
3. Record $V$ and $I$ ; calculate $R = V / I$ .
4. Repeat for different lengths.
Hazard Management: To prevent the wire from getting hot, use a low potential difference and switch the power off between readings.

The National Grid and Transformers

The National Grid System:
- Step-up Transformers: Increase potential difference and reduce current. This minimizes heating in cables and reduces energy loss, increasing efficiency. They have more turns on the secondary coil.
- Step-down Transformers: Decrease potential difference to a safe domestic level ( $230\,V$ ). They have fewer turns on the secondary coil.

Particle Model and Density

Density Formula: $\text{density} = \frac{\text{mass}}{\text{volume}}$
Determining Density of Irregular Objects:
1. Measure mass with a digital balance.
2. Use a Eureka (displacement) can filled to the spout with water.
3. Lower the object and collect displaced water in a measuring cylinder.
4. The volume of displaced water is the volume of the object.
Error Management: Repeat measurements to reduce random errors.
- Uncertainty is calculated as: $\text{Uncertainty} = \frac{\text{range}}{2}$ .
Experimental Limits: It is difficult to identify specific metals (e.g., Nickel vs Copper at $9,000\,kg/m^3$ ) based only on density due to experimental uncertainties or proximity of values.

Gas Pressure and Temperature

Temperature Influence: As temperature increases at constant volume, particles gain kinetic energy and move faster. Collisions with container walls are more frequent and forceful.
- $P = \frac{F}{A}$ , therefore pressure increases.
Volume Influence: As volume decreases at constant temperature, particles are more concentrated (closer together). This results in more frequent collisions with the walls, increasing pressure.

Radioactivity: Properties and Effects

Types of Radiation:
- Alpha ( $\alpha$ ): Symbols: $241$ . Range in air: < 5\,cm. Blocked by: Skin/Paper. Ionising power: High.
- Beta ( $\beta$ ): Range in air: $\approx 1\,m$ . Blocked by: $3\,mm$ Aluminium foil. Ionising power: Low.
- Gamma ( $\gamma$ ): Range in air: > 1\,km. Blocked by: Lead/Concrete. Ionising power: Very low.
Half-Life Calculations: The time taken for the count rate or mass to halve.
- Example: Initial $100\,g$ of Cobalt-60 with a half-life of $5\,years$ ; after $15\,years$ (3 half-lives), the remaining mass is $\frac{1}{8} = 12.5\,g$ .
- Example 2: Counts drop from $1600 \rightarrow 800 \rightarrow 400 \rightarrow 200$ over three half-lives.
Irradiation vs. Contamination:
- Irradiation: Exposing an object to nuclear radiation; the object does not become radioactive.
- Contamination: Unwanted presence of radioactive atoms on other materials; hazard originates from the decay of these atoms.
Detection Challenges: Background radiation is always present. Radioactive decay is a random process, making it difficult to determine the exact time a low count rate is reached because the signal is lost in the "noise."