SET 08

🎯 Objectives: TOWARD NECTA Physics - Set 8 Questions and Answers

SET 8: NECTA Form Four Physics Conceptual Questions and Answers

  1. What is a scalar quantity? Give two examples.
    Answer: A scalar quantity has magnitude only, no direction.
    Examples: Temperature, mass.
  2. Define vector quantity and give two examples.
    Answer: A vector quantity has both magnitude and direction.
    Examples: Velocity, force.
  3. Why does light bend when it passes from air to water?
    Answer: Light changes speed when passing between different media, causing it to change direction (refraction).
    Example: A straw in a glass of water appears bent.
  4. Explain how an electric generator produces electricity.
    Answer: Mechanical energy rotates a coil in a magnetic field, inducing an electric current by electromagnetic induction.
    Example: Hydroelectric power stations.
  5. State the difference between conductors and insulators.
    Answer: Conductors allow electric current to flow easily; insulators resist current.
    Examples: Copper is a conductor; rubber is an insulator.
  6. What is meant by work done?
    Answer: Work done is the product of force applied and displacement in the direction of force.
    Example: Lifting a box from the floor.
  7. Why does a bicycle slow down when brakes are applied?
    Answer: Friction between brake pads and wheel converts kinetic energy into heat, slowing the bike.
    Example: Braking before a stop sign.
  8. Explain how heat transfer by convection occurs.
    Answer: Hot fluid rises and cold fluid sinks, creating a circulation that transfers heat.
    Example: Warm air rising from a heater.
  9. What causes a rainbow?
    Answer: Dispersion, reflection, and refraction of sunlight in raindrops.
    Example: Rainbows appear after rain showers.
  10. Why does sound become faint as you move away from the source?
    Answer: Sound energy spreads over a larger area, reducing intensity.
    Example: Voices become quieter when walking away.
  11. State Ohm’s Law.
    Answer: The current flowing through a conductor is directly proportional to the voltage across it, provided temperature remains constant.
    Formula: V = IR
  12. What is the use of a fuse in electrical circuits?
    Answer: Protects circuits by melting and breaking the connection when current is too high.
    Example: Household wiring safety.
  13. Why do ice cubes float on water?
    Answer: Ice is less dense than water.
    Example: Floating ice in drinks.
  14. Explain why metals are shiny.
    Answer: Free electrons reflect light efficiently from the surface.
    Example: Polished silverware.
  15. Define acceleration.
    Answer: Rate of change of velocity with time.
    Example: A car increasing its speed.
  16. Why does the moon shine at night?
    Answer: The moon reflects sunlight.
    Example: Full moon visible at night.
  17. What is resonance?
    Answer: Increase in amplitude when frequency of forced vibrations matches the natural frequency.
    Example: Swing pushed at natural frequency.
  18. Why is sound faster in solids than in gases?
    Answer: Particles are closer and transmit vibrations more quickly.
    Example: Hearing a train through the rail.
  19. What is the principle of a hydraulic lift?
    Answer: Pressure applied to a confined fluid is transmitted equally in all directions.
    Example: Car jacks.
  20. Why does a glass prism separate white light into colors?
    Answer: Different wavelengths refract differently (dispersion).
    Example: Rainbow formation.
  21. Define power in physics.
    Answer: Rate of doing work or transferring energy.
    Formula: Power = Work done / Time.
  22. Explain the term ‘specific heat capacity’.
    Answer: Amount of heat needed to raise the temperature of 1 kg of a substance by 1°C.
    Example: Water has high specific heat capacity.
  23. Why do stars twinkle?
    Answer: Atmospheric turbulence causes variations in light direction.
    Example: Twinkling visible on clear nights.
  24. What is the difference between speed and velocity?
    Answer: Speed is scalar (magnitude only); velocity is vector (magnitude and direction).
    Example: 60 km/h is speed; 60 km/h east is velocity.
  25. Why do we wear black clothes in winter?
    Answer: Black absorbs more heat from sunlight.
    Example: Wearing black jackets keeps us warm.
  26. Explain why friction is both useful and harmful.
    Answer: Useful for walking, brakes; harmful causes wear and energy loss.
    Example: Car tires grip roads; engine parts wear due to friction.
  27. Define wave frequency.
    Answer: Number of waves passing a point per second.
    Unit: Hertz (Hz).
  28. What is meant by ‘latent heat of fusion’?
    Answer: Heat needed to change 1 kg of a solid into liquid at melting point without temperature change.
    Example: Ice melting to water.
  29. Why do metals conduct electricity but plastics do not?
    Answer: Metals have free electrons; plastics have none.
    Example: Copper wires vs plastic casing.
  30. What is the effect of increasing the temperature on gas pressure if volume is constant?
    Answer: Pressure increases due to increased molecular collisions.
    Example: Pressure cooker safety valves.

📖 Reference Book: N/A

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