GCSE Physics Practical Notes (AQA) Paper 1 And 2

Variables: Understand the three types of variables:
- Independent Variable: The variable you change.
- Dependent Variable: The variable that changes as a result; this is measured.
- Controlled Variables: Variables kept constant to ensure accuracy.
Equipment Identification: Always specify the equipment used for measurements (e.g., "measure the length using a ruler"). This can earn you extra marks.
Measurement Accuracy: Discuss methods to reduce errors and uncertainties, like aligning your eye level with the measurement mark (to avoid parallax error).
Repeat Measurements: Encourage conducting multiple readings to calculate an average for more reliable results.
Bullet Point Format: Writing in bullet points is encouraged; clarity aids the examiner in tracking your points.
Proper Language: Use full sentences and formal language in your responses, avoiding overly casual phrases.

Definition: Specific Heat Capacity (SHC) is the energy required to raise 1 kg of a substance by 1°C.
Experiment Setup: Insert an electrical heater into a beaker of water or a block of metal.
Measurements:
- Record the mass and initial temperature with a thermometer.
- Measure the temperature change every 20 seconds:
- Dependent variable: Temperature.
Power Calculations:
- Use an ammeter and voltmeter to determine current and potential difference (PD).
- Calculate power as: P = IV (where $I$ is current and $V$ is voltage).
SHC Formula:
- Rearrange to: SHC = \frac{Q}{m \Delta T} (where $Q$ is energy in joules, $m$ is mass, and $\Delta T$ is temperature change).

Objective: Investigate the relationship between the length of a wire and its resistance.
Materials: Use constantan wire for consistent resistance when heated.
Setup Details:
- Connect wires to a battery, an ammeter (in series), and a voltmeter (in parallel).
Procedure:
- Change the distance between crocodile clips to vary wire length; measure with a meter rule.
- Calculate resistance using Ohm's Law: R = \frac{V}{I} .
Resulting Relationship: Plot resistance against length; expect a straight line through the origin demonstrating direct proportionality.

Experiment Purpose: Determine how current changes with varying potential difference (PD).
Setup:
- Connect a fixed resistor with a variable resistor in series.
- Use voltmeter (parallel) and ammeter (series) to measure PD and current, respectively.
Data Collection: Reverse the battery for negative PD and current values.
Graphing Results:
- For a fixed resistor: expect a straight line (ohmic).
- For a filament bulb: expect a curve reflecting nonlinear resistance.
- A diode allows current in one direction only; exhibit high resistance in the reverse direction.

Finding Density of Solids:
- Measure mass using a top pan balance.
- For regular shapes, measure dimensions to calculate volume; for irregular shapes, use water displacement.
Density Calculation Formula: \text{Density} = \frac{\text{Mass}}{\text{Volume}} .
Solution Density: Pour solution into a zeroed measuring cylinder and measure mass.
Example: Pure water's density is 1 g/cm³; a 1.2 g/cm³ salt solution indicates 0.2 g/cm³ concentration.

Objective: Determine the spring constant.
Setup: Fix one end of a spring; hang slotted masses to measure extension.
Measurement of Extension: Track extension accurately using a ruler aligned with the spring's bottom.
Force Calculation: F = mg (with $g = 9.8 ext{ m/s}^2$).
Data Presentation: Plot force against extension; the gradient indicates the spring constant (k).

Purpose: Verify F = ma using slotted masses attached to a trolley.
Setup: Place the trolley on a track with a string over a pulley; measure acceleration through light gates or stopwatch.
Maintain Mass: Keep total mass constant by balancing added masses on the trolley.
Force Calculation: Again F = mg ; plot force vs. acceleration to yield a direct proportional relationship.

Ripple Tank Experiment:
- Project imagery of waves using light; measure wavelength by counting 10 waves and dividing.
- Introduce frequency changes to analyze wavelength adjustment; use wave speed equation: V = f\lambda .
Stationary Waves on String:
- Adjust frequency to achieve a simple stationary wave; length to pulley equals half the wavelength.

Leslie Cube Experiment: Fill with hot water, measure infrared emission from various surfaces.
Key Findings: Matte black is best for emitting and absorbing infrared; shiny surfaces reflect well.

Triple Science Only: Wrap beakers of hot water in different insulating materials and record temperature loss over time.

Measurement Process: Shine light into a block; mark entry and exit points to measure angles of incidence and refraction.
Calculations: For various angles of incidence, calculate \frac{\sin(i)}{\sin(r)} to find a constant for the refractive index.