Required Practicals – IGCSE Edexcel Physics (4PH1)

Aim

To investigate how distance, time and speed are related for a moving object, e.g. a toy car down a ramp.

Apparatus

• Toy car / trolley
• Ramp or sloped board + books
• Metre ruler / tape measure
• Stopwatch (or light gates if available)

Method (exam-style)

• Set up a ramp at a fixed angle on the bench.
• Measure and mark several distances from the top (e.g. 0.2 m, 0.4 m, 0.6 m…).
• Release the car from rest at the top; start the timer as it passes the starting point and stop it at each mark.
• Repeat each distance 3 times and calculate a mean time.
• Calculate average speed at each distance: speed = distance ÷ time.
• Plot a distance–time or speed–time graph and describe the motion.

Variables

• Independent – distance travelled (or starting height).
• Dependent – time taken (and calculated speed).
• Controls – same car, same ramp angle, same surface, same release point.

Key Ideas in Exams

• Distance–time curve is not a straight line → acceleration.
• Reaction time and stopwatch use are big sources of error.
• Improvement: use light gates, longer distances, repeat readings.

Often appears as: “Describe how to measure the acceleration of a trolley / car down a ramp.”

Aim

To investigate how the extension of a spring (or wire / rubber band) depends on the force applied.

Apparatus

• Clamp stand, boss and clamp
• Spring (or rubber band / metal wire)
• Slotted masses + mass hanger
• Metre ruler (with mm)

Method

• Clamp the spring securely and hang a small mass from it.
• Measure the original length of the spring with a ruler at eye level.
• Add masses in steps (e.g. 50 g each), allowing the spring to come to rest each time.
• Measure the new length each time and calculate extension = new length − original length.
• Plot a graph of force (weight = m g) vs extension.
• Use the straight-line region to discuss Hooke’s law (F ∝ extension).

Variables

• Independent – force (weight) added.
• Dependent – extension of the spring.
• Controls – same spring, same mass steps, ruler zero position, avoid swinging.

Key Ideas

• Linear section of graph: Hooke’s law, gradient = spring constant.
• Beyond limit of proportionality, graph curves and Hooke’s law no longer holds.
• Work done on spring = area under F–extension graph.

Common exam line: “Describe how to investigate the relationship between force and extension for a spring.”

Aim

To show how insulating materials become charged when rubbed and how they interact.

Apparatus

• Polythene rod, acetate rod
• Dry cloth / duster
• Small pieces of paper or a thin water stream
• Suspended rod / homemade gold-leaf electroscope (optional)

Method

• Hold a neutral rod near small pieces of paper – little or no effect.
• Rub the rod with the dry cloth, then bring it close to the paper – observe attraction.
• Repeat with a different material (e.g. acetate vs polythene) and compare behaviour.
• Hang one charged rod by a thread and bring another rod (charged the same way or the opposite way) close to it.
• Observe attraction (unlike charges) or repulsion (like charges).

Variables & Key Ideas

• Friction transfers electrons from one material to the other.
• The object that gains electrons becomes negatively charged; the other becomes positive.
• Like charges repel, unlike charges attract.

Exam trap: always talk about movement of electrons, not “movement of protons”.

Aim

To investigate how a light ray bends when entering/leaving glass, and to measure the refractive index of glass.

Apparatus

• Ray box + narrow slit
• Rectangular glass block
• A4 paper, pencil, ruler, protractor

Method (glass block)

• Place the glass block on paper and draw around it.
• Shine a single ray into one side of the block; mark its path entering and leaving the block with crosses.
• Remove the block, join the crosses, and draw the normal at the entry point.
• Measure angle of incidence i and angle of refraction r.
• Repeat for different angles of incidence, record values of i and r.
• Use n = sin i ÷ sin r to calculate refractive index; find an average value.

Variables

• Independent – angle of incidence i.
• Dependent – angle of refraction r.
• Controls – same glass block, same colour of light, room conditions.

Key Ideas

• Light bends towards the normal when entering a denser medium (glass), away when leaving.
• Refractive index should be roughly constant for each angle if measured carefully.
• Total internal reflection and critical angle appear when light goes from glass to air at large angles.

In exam answers, always mention: draw around the block, mark rays with crosses, draw normal, measure angles with a protractor.

Aim

To measure the speed of sound in air using distance and time measurements.

Apparatus

• Two people with wooden blocks (or starter pistol)
• Stopwatch
• Long measuring tape (e.g. 100 m)

Method (simple echo / timing method)

• Measure a long distance (e.g. 100 m) between source and observer.
• Person A makes a sharp sound (clap / blocks) while Person B starts timing when they see the action.
• Person B stops timing when they hear the sound.
• Repeat several times; calculate a mean time.
• Estimate speed of sound: v = distance ÷ time (or 2 × distance for echo method).

Variables & Exam Points

• Independent – distance between source and observer (if repeated with different distances).
• Dependent – measured time.
• Controls – same environment, same sound, same timing method.
• Reaction time is a big error → improve by repeating, using longer distances, or microphones/data logger.

Aim

To measure the frequency of a sound wave using an oscilloscope trace.

Apparatus

• Microphone
• Oscilloscope (or data logger with screen)
• Signal generator or tuning fork / speaker

Method

• Connect the microphone to the oscilloscope input.
• Produce a constant sound using a signal generator + speaker (or tuning fork close to the microphone).
• Adjust the time base so that several complete waves are visible on the screen.
• Measure the time period T (e.g. length of 5 waves ÷ 5).
• Calculate frequency: f = 1 / T.

Key Ideas

• Higher frequency → more cycles per second → waves closer together on the screen.
• Larger amplitude on screen → louder sound, but same pitch (frequency).

Exams like: “Explain how you would measure the frequency of a sound wave using an oscilloscope.”

Aim

To compare how conduction, convection and radiation transfer energy and how insulation can reduce transfers.

Examples (you don’t have to quote all – just one clearly in an exam)

• Conduction – waxed drawing pins on a metal bar heated at one end.
• Convection – coloured crystals in water heated from below, or smoke in a convection tank.
• Radiation – Leslie cube or metal cans with different surface colours, filled with hot water.

Conduction Example

• Fix drawing pins along a metal bar using wax, then heat one end in a flame.
• Record the time taken for each pin to fall as the wax melts.
• Pins near the flame fall first → heat travels along the metal by conduction.

Key Ideas

• Metals conduct well because they have free electrons.
• Liquids and gases transfer energy mainly by convection currents.
• Dark, matt surfaces are better absorbers/emitters of infrared than light, shiny ones.

In exam answers, choose one method and describe it clearly with what you change, measure, and observe.

Aim

To determine the density of solids (regular and irregular) and liquids using measurements of mass and volume.

Apparatus

• Balance
• Measuring cylinder
• Ruler / calipers
• Solid blocks (regular shapes) and irregular objects
• Liquids (e.g. water, oil)

Method (regular solid)

• Measure the mass of the block with a balance.
• Measure its length, width and height with a ruler (in m).
• Calculate volume: V = l × w × h.
• Calculate density: ρ = m / V.

Method (irregular solid)

• Measure mass with a balance.
• Fill a measuring cylinder with water and record the initial volume.
• Gently lower the object into the water; read the new volume.
• Volume of object = final volume − initial volume; then ρ = m / V.

Variables & Ideas

• Always use consistent units (kg and m³ or g and cm³).
• Read the meniscus at eye level for volume.
• Dry objects before weighing after water displacement.

Typical exam question: “Describe an experiment to find the density of an irregular object such as a stone.”

Aim

To determine the specific heat capacity of a solid or liquid using an electrical heater.

Apparatus

• Block of material with heater hole or beaker of water
• Immersion heater
• Thermometer
• Balance
• Stopwatch
• Ammeter, voltmeter, power supply (for accurate electrical energy)

Method (simplified)

• Measure the mass m of the block / water.
• Measure initial temperature.
• Switch on the heater for a measured time t, recording voltage V and current I.
• Measure final temperature and find temperature rise ΔT.
• Energy supplied electrically: E = I V t.
• Use ΔQ = m c ΔT → c = E / (m ΔT).

Key Points

• Some energy lost to surroundings → answer is an estimate.
• Reduce losses using insulation and a lid.
• Stir gently to keep temperature uniform.

Aim

To map the magnetic field of a bar magnet and between two bar magnets using iron filings or compasses.

Apparatus

• Bar magnets
• Paper / card
• Iron filings (or many small plotting compasses)

Method (iron filings)

• Place the magnet under a sheet of paper.
• Sprinkle iron filings lightly over the paper.
• Tap the paper gently to allow filings to line up with the field.
• Observe the pattern; sketch field lines from N to S.
• Repeat with two magnets arranged N–S (strong field between) and N–N (repulsion pattern).

Key Ideas

• Field lines run from north pole to south pole.
• Lines closer together → stronger field (especially between N and S facing each other).
• Compasses are tiny magnets that align with the field.

Aim

To compare how alpha, beta and gamma radiation are absorbed by different materials.

Apparatus (or simulation)

• Radioactive sources (α, β, γ) – or computer simulation
• Thin paper, aluminium sheets, thick lead
• Geiger–Müller (GM) tube and counter

Method

• Measure and record background count first.
• Place source at a fixed distance from the GM tube; record count rate (minus background).
• Insert paper between source and detector; measure count rate again.
• Repeat with aluminium sheet, then with thick lead.
• Compare which radiations are stopped or reduced by which materials.

Key Ideas

• α: stopped by paper or a few centimetres of air.
• β: passes paper, mostly stopped by thin aluminium.
• γ: passes both paper and Al, intensity reduced by thick lead.
• Always subtract background count when analysing data.

Safety: use tongs, keep sources pointed away from body, minimise time, maximise distance, use shielding, follow teacher’s instructions.