The Physics Practical (Paper 3) accounts for 40% of your total WAEC Physics grade, yet many students lose easy marks due to poor experimental technique, incorrect recordings, or graph plotting errors.
This comprehensive guide covers every equipment you'll encounter, proper experimental procedures, data recording techniques, and the graph plotting skills that separate A-grade students from the rest.
🔬 Understanding WAEC Physics Paper 3 Format
Paper Structure:
- Duration: 2 hours 50 minutes (2hrs 40min practical + 10min reading time)
- Sections: Usually 3 experiments (pick 3 from 4 or all 3 compulsory)
- Topics Covered:
- Mechanics (pendulum, inclined plane, springs)
- Heat (specific heat capacity, heat transfer)
- Light (mirrors, lenses, refraction)
- Electricity (resistors, voltmeters, ammeters)
- Alternative to Practical: For schools without labs, similar paper with data provided
💡 Marking Scheme Reality:
Examiners allocate marks as follows:
- Procedure & Setup: 20%
- Accurate Readings: 30%
- Graph Plotting: 25%
- Calculations & Conclusions: 25%
âš™ï¸ Essential Physics Laboratory Equipment
1. Measuring Instruments
Meter Rule / Measuring Tape
- Use: Linear measurements (length, distance, height)
- Precision: ±0.1 cm (smallest division is 1mm = 0.1cm)
- Common Mistakes: Not reading at eye level (parallax error), using damaged/bent rulers
- Pro Tip: Always measure from the 1cm mark, not 0cm (worn edges)
Vernier Calipers
- Use: Precise small measurements (diameter, thickness)
- Precision: ±0.01 cm
- Reading Method: Main scale reading + (Vernier division × 0.01)
- Pro Tip: Close jaws gently - excessive force gives false readings
Micrometer Screw Gauge
- Use: Very precise measurements (wire diameter, thin objects)
- Precision: ±0.001 cm
- Zero Error: Always check and record zero error before measuring
- Pro Tip: Use ratchet stop to ensure consistent pressure
Stopwatch / Stopcock
- Use: Time measurements (oscillations, reactions)
- Precision: ±0.01 s
- Best Practice: Measure 20 oscillations, divide by 20 for period
- Pro Tip: Start counting from zero, not one!
2. Force and Mass Equipment
Spring Balance / Newton Meter
- Use: Measuring force/weight in Newtons
- Reading: Read at pointer position, not hook
- Zero Check: Must read zero when unloaded
Weights / Masses
- Types: Slotted masses (10g, 20g, 50g, 100g, 200g)
- Important: Mass (kg) ≠Weight (N). Weight = mass × 10 m/s²
Retort Stand & Clamps
- Use: Supporting apparatus vertically
- Setup: Heavy base, tight clamps, stable positioning
3. Electrical Equipment
Ammeter
- Connection: Always in SERIES with component
- Range: 0-1A or 0-5A (choose appropriate)
- Reading: Note if using × 0.1 or × 1 terminals
Voltmeter
- Connection: Always in PARALLEL across component
- Range: 0-5V or 0-15V
- Polarity: Red to positive, black to negative
Rheostat / Variable Resistor
- Use: Varying current in circuit
- Connection: In series, use terminals at ends and slider
Resistance Box
- Use: Providing known resistances
- Reading: Sum of all unplugged values
4. Optics Equipment
Plane Mirror
- Setup: Stand vertically, perpendicular to paper
- Ray Tracing: Use sharp pencil for pins
Converging/Diverging Lens
- Focal Length: Distance from lens to sharp image of distant object
- Object-Image Relationship: 1/f = 1/u + 1/v
Optical Pins
- Use: Marking ray paths
- Technique: Pin upright, view base alignment
📊 Graph Plotting Mastery
10 Commandments of Graph Plotting:
- Use Graph Paper Properly
- Leave 2cm margin all around
- Plot should occupy at least â…” of page
- Use clear, bold axes
- Choose Suitable Scales
- Use scales that make plotting easy (1, 2, 5, 10 units per cm)
- Avoid awkward scales like 3, 7, 9 per cm
- Both axes should be well-utilized
- Label Axes Correctly
- Format: "Quantity/Unit" (e.g., Time/s, Force/N)
- Independent variable on x-axis
- Dependent variable on y-axis
- Mark Points Accurately
- Use × or ⊕ symbols (not dots)
- Plot to ±½ small square precision
- Clear, visible marks
- Draw Line of Best Fit
- Use transparent ruler for straight lines
- Line should pass through/near most points
- Equal points on both sides of line
- DON'T join dot-to-dot!
- Use Pencil (HB) for Graphs
- Never use pen for plotting
- Allows corrections if needed
- Sharp pencil for precision
- Calculate Gradient/Slope
- Choose two points far apart ON THE LINE (not data points)
- Slope = (yâ‚‚ - yâ‚) / (xâ‚‚ - xâ‚)
- Show triangle on graph
- Include units in answer
- Find y-intercept
- Where line crosses y-axis (when x = 0)
- If origin not shown, extrapolate line
- State value with unit
- Give Graph a Title
- Format: "Graph of Y against X"
- Example: "Graph of Extension against Load"
- Centered at top of graph
- Show All Working
- Calculate slope on graph sheet
- Show substitution clearly
- State final answer distinctly
âš ï¸ Graph Errors That Cost Marks:
- ⌠Scale not stated or irregular
- ⌠Axes not labeled with units
- ⌠Graph too small (less than half page)
- ⌠Joining dot-to-dot instead of best fit line
- ⌠Calculating slope using data points instead of line points
- ⌠Using pen instead of pencil
- ⌠Slope calculation without units
🧪 Common WAEC Physics Experiments
Experiment 1: Simple Pendulum (Determining 'g')
Aim:
To determine the acceleration due to gravity using a simple pendulum
Apparatus:
Retort stand, thread (about 100cm), small bob, meter rule, stopwatch
Procedure:
- Suspend bob from thread, measure length L (to center of bob)
- Displace bob slightly (small angle < 10°), release
- Time 20 complete oscillations, repeat for accuracy
- Calculate period T = total time / 20
- Repeat for 5 different lengths
- Plot graph of T² against L
- Slope = 4π² / g, therefore g = 4π² / slope
Theory:
T = 2π√(L/g), therefore T² = (4π²/g) × L
Graph of T² vs L gives straight line through origin, slope = 4π²/g
Expected Result:
g ≈ 9.8 - 10.2 m/s² (accept ±5% due to experimental errors)
Experiment 2: Ohm's Law Verification
Aim:
To verify Ohm's law and determine resistance of a wire
Circuit Diagram:
[Battery] → [Rheostat] → [Ammeter] → [Wire/Resistor] → [Back to Battery]
[Voltmeter] parallel across wire
Procedure:
- Connect circuit as shown
- Adjust rheostat to get 5 different current readings
- Record corresponding voltages
- Tabulate I and V values
- Plot graph of V against I
- Calculate slope (resistance) and y-intercept
Theory:
V = IR (Ohm's Law), therefore graph of V vs I is straight line through origin
Slope = R (resistance in ohms)
Expected Result:
Straight line through or near origin, constant R value
Experiment 3: Refractive Index Determination
Aim:
To determine the refractive index of glass using a rectangular glass block
Apparatus:
Glass block, white paper, pins, protractor, ruler, soft pencil
Procedure:
- Place glass block on paper, trace outline
- Fix two pins (A, B) on incident side at angle to normal
- Looking through block, fix two pins (C, D) aligned with images of A, B
- Remove block, draw incident and emergent rays
- Draw normals, measure angles i and r
- Repeat for 4-5 different incident angles
- Plot graph of sin i against sin r
- Slope = refractive index n
Theory:
n = sin i / sin r (Snell's Law)
Expected Result:
n ≈ 1.5 for glass
📠Data Recording & Table Format
Perfect Data Table Structure:
| S/N | Load, F/N | Initial Length, Lâ‚€/cm | Final Length, L/cm | Extension, e = L - Lâ‚€/cm |
|---|---|---|---|---|
| 1 | 1.0 | 50.0 | 51.2 | 1.2 |
| 2 | 2.0 | 50.0 | 52.3 | 2.3 |
✅ Table Checklist:
- ✓ Title above table
- ✓ Column headings with quantities and units (Format: Quantity/Unit)
- ✓ Serial numbers (S/N) for readings
- ✓ Ruled lines (use pencil and ruler)
- ✓ Data aligned (use decimal points alignment)
- ✓ Consistent decimal places
- ✓ Show calculations for derived quantities
âš¡ Top Exam Day Tips
Before Exam Starts (10-minute reading time):
- Read all experiments quickly
- Choose experiments you're most confident with
- Check all apparatus provided are working
- Plan time allocation (3 experiments in 2hr 40min = ~50min each)
- Identify which graphs need to be plotted
During Experiment:
- ✓ Read procedure twice before starting
- ✓ Set up apparatus carefully, ensure stability
- ✓ Take readings at eye level (avoid parallax)
- ✓ Record immediately in table (don't trust memory!)
- ✓ Take at least 5 readings for graph experiments
- ✓ Check for consistent readings (repeat if strange value)
- ✓ Show ALL calculations step-by-step
- ✓ State precautions taken during experiment
Common Precautions to State:
- "Avoided parallax error by reading at eye level"
- "Ensured apparatus was stable/rigid"
- "Repeated readings for accuracy"
- "Avoided zero error on measuring instruments"
- "Ensured tight electrical connections"
- "Used small oscillation angles" (for pendulum)
âš ï¸ Never Do This:
- ⌠Fabricate data (examiners can tell!)
- ⌠Skip showing working for calculations
- ⌠Forget to include units in answers
- ⌠Rush readings (accuracy > speed)
- ⌠Leave questions blank (attempt all parts)
🎯 Final Preparation Checklist
1 Week Before Practical:
- ✓ Practice setting up common experiments
- ✓ Master vernier calipers and micrometer screw gauge readings
- ✓ Plot 3-5 practice graphs with proper scales
- ✓ Calculate slopes and intercepts accurately
- ✓ Memorize formula sheet for each topic
- ✓ Review how to connect ammeters and voltmeters
- ✓ Practice drawing ray diagrams
Items to Bring:
- ✓ Sharp HB pencils (at least 3)
- ✓ Eraser and sharpener
- ✓ Transparent ruler (30cm)
- ✓ Calculator (in good working order)
- ✓ Graph sheets (provided or bring extra)
- ✓ Set of mathematical instruments
âš›ï¸ Master Physics Concepts
Practice Physics theory questions and strengthen your understanding before the practical exam!
Practice Physics Now