Cheat Sheet (Copy)

IGCSE / O Level Physics – Alternate to Practical (ATP) Paper Cheat Sheet

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 1. General Rules for ATP Paper

• Use a sharp HB pencil for diagrams, graphs, and constructions.
• Read all units and convert if needed (e.g. cm to m).
• Give final numerical answers with correct units and significant figures.
• Always show working in calculations (even for 1-mark answers).
• Draw diagrams large, neat, and accurately labeled.
• Use a ruler for all straight lines (light rays, graphs, circuits).

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 2. Key Experimental Skills Tested

Skill	Common Question Style
Measurement	“Measure the length”, “Read the ammeter/voltmeter”
Observation	“What do you notice about…”
Graphing	“Plot a graph of…”, “Determine the gradient”
Analysis	“Explain the trend”, “Suggest reason for anomaly”
Planning	“Design an experiment to investigate…”

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🔌 3. Common Practical Topics

 A. Length and Time

• Use meter rule or vernier caliper for length.
• Use stopwatch or light gates for time.

✔️ Always measure perpendicularly to reduce parallax error.
✔️ Record multiple readings and take average for accuracy.

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B. Mass and Density

• Density = mass / volume
• Use balance for mass.
• For volume:
  • Regular object → use dimensions
  • Irregular → use displacement method (eureka can)

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C. Speed and Acceleration

• Speed = distance / time
• Acceleration = (final speed – initial speed) / time
• Use trolley on ramp, light gates, or timing card

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D. Forces and Newton’s Laws

• Use spring balances, pulley systems, or weights
• Measure force in newtons (N)

✔️ Direction and balancing of forces often tested in setups.

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E. Moments (Turning Effect)

• Moment = force × perpendicular distance
• Use balanced beam and weights
• Ensure pivot is clearly marked in diagrams

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 F. Hooke’s Law

• Investigate extension of spring:
  • Force vs Extension graph (straight line = obeys Hooke’s Law)
• Equipment: clamp stand, spring, masses, metre rule

✔️ Always measure original length and take extension = new length – original length

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G. Thermal Experiments

• Use thermometers, heaters, beakers, insulators
• Questions often ask about rate of heat loss or temperature change

✔️ Use same volume/mass, measure temp every minute, plot temp vs time

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H. Specific Heat Capacity

• E = mcΔT
  • E = energy (J), m = mass (kg), c = specific heat (J/kg°C), ΔT = temperature rise
• Use immersion heater, joulemeter, thermometer

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 I. Electrical Circuits

• Be able to:
  • Draw series and parallel circuits
  • Measure current (A) with ammeter (in series)
  • Measure voltage (V) with voltmeter (in parallel)

✔️ Use Ohm’s Law:
V = IR

✔️ Plot V vs I graphs to determine resistance (gradient = resistance)

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J. Resistors and Resistance

• Use different wires (lengths/thicknesses/materials)
• Keep voltage constant to compare current

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 K. Light (Ray Diagrams)

• Investigate reflection and refraction

Reflection:

• Use ray box, mirror, protractor
• Measure angle of incidence = angle of reflection

Refraction:

• Use glass block, ray box, measure angles
• Snell’s Law:
  n = sin(i)/sin(r)

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 L. Lenses (Converging/Convex)

• Set up object (e.g. lit candle), lens, and screen
• Measure:
  • Object distance (u)
  • Image distance (v)
• Use lens formula:
  1/f = 1/u + 1/v

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M. Sound

• Use microphone, signal generator, oscilloscope
• May measure wavelength, frequency, speed

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 4. Graphs in ATP Paper

Type	Example	Notes
Line graph	Temp vs Time, Force vs Extension	Must use even scale, draw best-fit line
Gradient	Velocity vs Time → gives acceleration	Gradient = Δy / Δx
Area under graph	Force vs Distance → gives Work	Estimate area carefully

✔️ Label axes with units
✔️ Use at least 50% of graph space

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5. Common Errors to Avoid

Mistake	Correct Way
Measuring at angle (parallax)	Always eye-level and perpendicular
Wrong units	Use m, s, °C, N, V, A etc.
No repeats or averages	Always take multiple readings
No scale or axis label in graph	Always write quantity + unit on each axis
Using ruler for curved lines	Only use ruler for straight lines or axes

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 6. Safety Precautions (When Asked)

Scenario	Safety Tip
Heating water	Use goggles, handle glassware with tongs
Electrical circuits	Keep circuits off when setting up
Glass or mercury thermometer	Handle gently, dispose if broken
Sharp objects (e.g. metal strips)	Handle with care, use gloves if needed

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 7. High-Scoring Exam Tips

• Use the word “repeat and average” in any data collection plan
• Always state control variables: “keep mass/voltage/time constant”
• When asked for a method, always write step-by-step, including equipment
• Use bullet points or numbered steps for clarity
• Quote data from graphs when interpreting trends
• Estimate uncertainties or improvements when asked: e.g., “use digital stopwatch for better timing”

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📌 8. Quick Reference Equations (Common in ATP)

• Speed = distance / time
• Density = mass / volume
• Moment = force × distance
• Work = force × distance
• E = mcΔT
• V = IR
• Power = energy / time = VI