Cambridge IGCSE Physics Structured Questions

Cambridge IGCSE Physics: Structured Questions

This section contains 20 structured questions designed to test your understanding of key IGCSE Physics concepts. Answer all questions clearly, showing your working where appropriate.

  1. Question 1: Measurement and Density

    A student measures the length of a rod using a ruler graduated in millimetres. The reading is 12.5 cm.

    1. State the precision of the ruler.
    2. Convert 12.5 cm into metres.
    3. If the rod has a mass of 150 g and a volume of 20 cm3, calculate its density in g/cm3.

  2. Question 2: Forces and Motion

    A car of mass 1200 kg accelerates uniformly from rest to a speed of 20 m/s in 8.0 s.

    1. Calculate the acceleration of the car.
    2. Determine the resultant force acting on the car.
    3. State Newton's First Law of Motion.

  3. Question 3: Work, Energy, Power

    A boy pushes a box with a force of 50 N over a distance of 10 m in 5.0 s.

    1. Calculate the work done by the boy.
    2. Calculate the power developed by the boy.
    3. State the principle of conservation of energy.

  4. Question 4: Pressure

    A block of wood has dimensions 2.0 m x 1.0 m x 0.5 m and a mass of 400 kg.

    1. Calculate the weight of the block. (Take g = 10 N/kg)
    2. Calculate the maximum pressure exerted by the block on a surface.
    3. Explain why a sharp knife cuts more effectively than a blunt knife.

  5. Question 5: Thermal Physics - Temperature and Heat Capacity

    A 2.0 kg block of a metal is heated from 20 ℃ to 70 ℃. The specific heat capacity of the metal is 400 J/(kg℃).

    1. Calculate the change in temperature in Kelvin.
    2. Calculate the amount of heat energy absorbed by the metal block.
    3. Explain the difference between heat and temperature.

  6. Question 6: Thermal Physics - Heat Transfer

    Explain the three modes of heat transfer, giving one example for each.

    1. Conduction
    2. Convection
    3. Radiation

  7. Question 7: Waves - Properties

    A wave has a frequency of 50 Hz and a wavelength of 0.2 m.

    1. Calculate the speed of the wave.
    2. Define amplitude of a wave.
    3. Distinguish between transverse and longitudinal waves.

  8. Question 8: Light - Reflection

    A light ray strikes a plane mirror at an angle of incidence of 35˚.

    1. State the angle of reflection.
    2. Draw a ray diagram to show the reflection of this light ray.
    3. List two characteristics of the image formed by a plane mirror.

  9. Question 9: Light - Refraction and Lenses

    A converging lens has a focal length of 15 cm. An object is placed 25 cm from the lens.

    1. State the phenomenon that occurs when light passes from air into a glass lens.
    2. Describe the nature of the image formed (real/virtual, inverted/upright, magnified/diminished).
    3. Draw a ray diagram to confirm your answer to (b).

  10. Question 10: Sound Waves

    A student claps their hands in front of a wall and hears an echo after 0.50 s. The speed of sound in air is 340 m/s.

    1. Explain how an echo is formed.
    2. Calculate the distance between the student and the wall.
    3. State one practical application of sound waves, other than communication.

  11. Question 11: Electromagnetic Spectrum

    List the seven main regions of the electromagnetic spectrum in order of increasing wavelength.

  12. Question 12: Static Electricity

    A plastic rod is rubbed with a cloth and becomes negatively charged.

    1. Explain how the rod became negatively charged.
    2. Describe what happens when the negatively charged rod is brought near a neutral metallic sphere.
    3. State one hazard of static electricity.

  13. Question 13: Current, Voltage, Resistance

    A resistor has a resistance of 10 Ω. A current of 0.5 A flows through it.

    1. Calculate the potential difference across the resistor.
    2. Define electric current.
    3. State Ohm's Law.

  14. Question 14: Electrical Circuits - Series and Parallel

    Two resistors, R1 = 2 Ω and R2 = 3 Ω, are connected to a 6 V power supply.

    1. Calculate the total resistance if they are connected in series.
    2. Calculate the total current flowing from the supply if they are connected in series.
    3. Calculate the total resistance if they are connected in parallel.

  15. Question 15: Electrical Power and Energy

    An electric heater has a power rating of 2 kW when connected to a 240 V mains supply.

    1. Calculate the current flowing through the heater.
    2. Calculate the energy consumed by the heater in 3 hours, in joules.
    3. Explain why household electrical wiring uses fuses or circuit breakers.

  16. Question 16: Magnetism and Electromagnetism

    Describe an experiment to show the magnetic field pattern around a bar magnet. Include the apparatus used and the procedure.

  17. Question 17: Motors and Generators

    Explain the basic principle of operation of a simple DC electric motor.

  18. Question 18: Transformers

    A step-down transformer has a primary coil with 1000 turns and a secondary coil with 100 turns. The input voltage is 240 V.

    1. Calculate the output voltage.
    2. Explain why transformers are used in the transmission of electrical power.

  19. Question 19: Radioactivity - Alpha, Beta, Gamma

    Compare alpha (α), beta (β), and gamma (γ) radiations in terms of their penetrating power and ionising effect.

    Radiation TypePenetrating PowerIonising Effect
    Alpha (α)
    Beta (β)
    Gamma (γ)

  20. Question 20: Nuclear Physics - Half-life

    Radioactive decay is a random and spontaneous process.

    1. Explain what is meant by a random process in the context of radioactive decay.
    2. Define the term 'half-life'.
    3. A sample of a radioactive isotope has a half-life of 6 hours. If its initial activity is 400 Bq, what will its activity be after 18 hours?

Answer Key

  1. Answer to Question 1

    1. 1 mm or 0.1 cm
    2. 0.125 m
    3. Density = Mass / Volume = 150 g / 20 cm3 = 7.5 g/cm3

  2. Answer to Question 2

    1. Acceleration = (Final velocity - Initial velocity) / Time = (20 m/s - 0 m/s) / 8.0 s = 2.5 m/s2
    2. Resultant force = Mass × Acceleration = 1200 kg × 2.5 m/s2 = 3000 N
    3. An object will remain at rest or in uniform motion in a straight line unless acted upon by a resultant external force.

  3. Answer to Question 3

    1. Work done = Force × Distance = 50 N × 10 m = 500 J
    2. Power = Work done / Time = 500 J / 5.0 s = 100 W
    3. Energy cannot be created or destroyed, but can only be transferred from one form to another.

  4. Answer to Question 4

    1. Weight = Mass × g = 400 kg × 10 N/kg = 4000 N
    2. Maximum pressure occurs when the smallest area is in contact with the surface. Smallest area = 1.0 m × 0.5 m = 0.5 m2. Pressure = Force / Area = 4000 N / 0.5 m2 = 8000 Pa
    3. A sharp knife has a very small contact area, thus exerting a large pressure for a given force, making it easier to cut.

  5. Answer to Question 5

    1. Change in temperature = 70 ℃ - 20 ℃ = 50 ℃. Change in temperature in Kelvin is the same, 50 K.
    2. Heat energy absorbed = mcΔT = 2.0 kg × 400 J/(kg℃) × 50 ℃ = 40 000 J
    3. Heat is a form of energy transfer, while temperature is a measure of the average kinetic energy of the particles within a substance.

  6. Answer to Question 6

    1. Conduction: Transfer of heat through direct contact, mainly in solids, by vibrations of particles and free electron movement. Example: Heat travels along a metal spoon when one end is placed in hot soup.
    2. Convection: Transfer of heat in fluids (liquids and gases) by the movement of heated particles (convection currents). Example: Boiling water in a pot; warmer water rises, cooler water sinks.
    3. Radiation: Transfer of heat through electromagnetic waves (infrared radiation) without requiring a medium. Example: Heat from the Sun reaching Earth; heat from a glowing fire.

  7. Answer to Question 7

    1. Speed = Frequency × Wavelength = 50 Hz × 0.2 m = 10 m/s
    2. Amplitude is the maximum displacement of a point on a wave from its equilibrium (rest) position.
    3. Transverse waves: Particle oscillations are perpendicular to the direction of wave propagation (e.g., light waves). Longitudinal waves: Particle oscillations are parallel to the direction of wave propagation (e.g., sound waves).

  8. Answer to Question 8

    1. Angle of reflection = Angle of incidence = 35˚
    2. [Ray diagram should show incident ray at 35˚ to the normal, reflected ray also at 35˚ to the normal, with arrows indicating direction.]
    3. Image is virtual, upright, laterally inverted, and the same size as the object. (Any two are sufficient)

  9. Answer to Question 9

    1. Refraction
    2. The image formed is real, inverted, and magnified.
    3. [Ray diagram should show an object placed between F and 2F, forming a real, inverted, magnified image beyond 2F on the other side of the lens.]

  10. Answer 10

    1. An echo is formed when sound waves reflect off a surface and return to the listener's ear with a perceptible delay.
    2. Total distance travelled by sound = Speed × Time = 340 m/s × 0.50 s = 170 m. Distance to wall = Total distance / 2 = 170 m / 2 = 85 m.
    3. Ultrasound for medical imaging (e.g., scans) or sonar for depth finding.

  11. Answer 11

    1. Radio waves
    2. Microwaves
    3. Infrared
    4. Visible light
    5. Ultraviolet
    6. X-rays
    7. Gamma rays

  12. Answer 12

    1. When the plastic rod is rubbed with the cloth, electrons are transferred from the cloth to the plastic rod, giving the rod a net negative charge.
    2. The negatively charged rod will repel free electrons in the metallic sphere to the far side, leaving the near side positively charged (induced charge separation). The sphere will be attracted to the rod.
    3. Lightning, sparks when refuelling aircraft, dust explosions in flour mills.

  13. Answer 13

    1. Potential difference (V) = Current (I) × Resistance (R) = 0.5 A × 10 Ω = 5 V
    2. Electric current is the rate of flow of electric charge.
    3. Ohm's Law states that the current flowing through a metallic conductor is directly proportional to the potential difference across its ends, provided its temperature and other physical conditions remain constant.

  14. Answer 14

    1. In series: Total resistance RT = R1 + R2 = 2 Ω + 3 Ω = 5 Ω
    2. In series: Total current I = V / RT = 6 V / 5 Ω = 1.2 A
    3. In parallel: 1/RT = 1/R1 + 1/R2 = 1/2 Ω + 1/3 Ω = 3/6 + 2/6 = 5/6 Ω-1. So, RT = 6/5 Ω = 1.2 Ω

  15. Answer 15

    1. Current I = Power P / Voltage V = 2000 W / 240 V ≈ 8.33 A
    2. Energy consumed E = Power P × Time t. Time = 3 hours = 3 × 3600 s = 10 800 s. E = 2000 W × 10 800 s = 21 600 000 J
    3. Fuses and circuit breakers are safety devices that protect electrical circuits and appliances from damage due to excessive current (overload or short circuit) by breaking the circuit.

  16. Answer 16

    Apparatus: Bar magnet, plotting compass (or iron filings), piece of paper.

    Procedure with Plotting Compass:

    1. Place the bar magnet on a flat surface and cover it with a piece of paper.
    2. Place a plotting compass near one pole of the magnet. Mark the direction the compass needle points.
    3. Move the compass to the position where its tail is at the previously marked point. Mark the new direction of the needle's head.
    4. Repeat this process until a complete line of force is drawn from one pole to the other.
    5. Repeat for several starting points to map the entire field.

    Procedure with Iron Filings:

    1. Place the bar magnet on a flat surface and cover it with a piece of paper.
    2. Gently sprinkle iron filings evenly over the paper.
    3. Tap the paper lightly. The iron filings will align themselves along the magnetic field lines.
    4. Observe and sketch the pattern.

  17. Answer 17

    A simple DC electric motor works on the principle of the motor effect (or Lorentz force). When a current-carrying conductor (a coil) is placed in a magnetic field, it experiences a force. In a motor, a rectangular coil is placed between the poles of a magnet. When current flows through the coil, one side experiences an upward force and the other side experiences a downward force. These two forces create a turning effect (torque) that makes the coil rotate. A commutator and brushes are used to reverse the direction of the current in the coil every half rotation, ensuring continuous rotation in one direction.

  18. Answer 18

    1. Using the transformer equation Vp/Vs = Np/Ns: 240 V / Vs = 1000 / 100. So, Vs = 240 V × (100 / 1000) = 24 V. The output voltage is 24 V.
    2. Transformers are used in power transmission to step up the voltage (and thus step down the current) for long-distance transmission. This reduces energy loss as heat (P = I2R) in the transmission cables, making power transmission more efficient. At the destination, step-down transformers are used to reduce the voltage to safe levels for domestic and industrial use.

  19. Answer 19

    Radiation TypePenetrating PowerIonising Effect
    Alpha (α)Very low (stopped by paper/skin)Very high
    Beta (β)Medium (stopped by a few mm of aluminium)Medium
    Gamma (γ)Very high (attenuated by thick lead/concrete)Very low

  20. Answer 20

    1. A random process means that it is impossible to predict when a particular unstable nucleus will decay. Each nucleus has an equal probability of decaying in a given time, but the exact moment of decay for an individual nucleus cannot be known.
    2. Half-life is the time taken for half of the radioactive nuclei in a sample to decay, or the time taken for the activity of a radioactive source to halve.
    3. After 6 hours (1 half-life): Activity = 400 Bq / 2 = 200 Bq.
      After 12 hours (2 half-lives): Activity = 200 Bq / 2 = 100 Bq.
      After 18 hours (3 half-lives): Activity = 100 Bq / 2 = 50 Bq.
#igcse#physics#cie#structured questions#exam preparation#revision#science#cambridge