SET 09

🎯 Objectives: TOWARD NECTA Physics - Set 9 Questions and Answers

SET 9: NECTA Form Four Physics Conceptual Questions and Answers

  1. What is meant by diffraction of waves?
    Answer: Diffraction is the bending of waves around obstacles or through small openings.
    Example: Sound waves bending around a corner.
  2. Explain how a convex lens forms an image.
    Answer: A convex lens converges parallel rays to a focus, forming real or virtual images depending on object distance.
    Example: Magnifying glasses form enlarged virtual images.
  3. Why do objects appear bent in water?
    Answer: Light refracts when passing from water to air, changing direction.
    Example: A stick partially in water looks broken.
  4. What is meant by specific heat capacity?
    Answer: Amount of heat required to raise 1 kg of a substance by 1°C.
    Example: Water’s specific heat capacity is 4200 J/kg°C.
  5. Describe the process of conduction.
    Answer: Transfer of heat through a solid by direct contact of particles.
    Example: Metal spoon heating up in hot water.
  6. Why is the resistance of a wire proportional to its length?
    Answer: Longer wires have more collisions between electrons and atoms, increasing resistance.
    Example: Extending an electrical cable increases resistance.
  7. What is Newton’s first law of motion?
    Answer: A body remains at rest or in uniform motion unless acted upon by an external force.
    Example: A book stays on a table until pushed.
  8. Why is a vacuum a good insulator?
    Answer: It contains no particles, so no heat transfer by conduction or convection.
    Example: Thermos flask uses vacuum to keep liquids hot or cold.
  9. Explain why ice is less dense than water.
    Answer: Ice molecules form an open hexagonal structure, increasing volume.
    Example: Ice cubes float in drinks.
  10. What causes static electricity?
    Answer: Build-up of electric charges on a surface due to friction.
    Example: Rubbing a balloon on hair.
  11. State the function of a diode.
    Answer: Allows current to flow in one direction only.
    Example: Used in rectifiers to convert AC to DC.
  12. Why is sound intensity measured in decibels (dB)?
    Answer: Because the human ear perceives sound logarithmically, decibels express intensity on a manageable scale.
    Example: Normal conversation is about 60 dB.
  13. What happens to pressure in a fluid as depth increases?
    Answer: Pressure increases due to the weight of fluid above.
    Example: Deep-sea divers experience higher pressure.
  14. Explain the difference between mass and weight.
    Answer: Mass is the amount of matter; weight is the force due to gravity acting on mass.
    Example: Mass is constant; weight varies with gravity.
  15. Why does a pendulum eventually stop swinging?
    Answer: Due to friction and air resistance converting mechanical energy to heat.
    Example: Clock pendulums need winding to keep moving.
  16. What is meant by the wavelength of a wave?
    Answer: The distance between two successive crests or troughs.
    Example: Radio waves have longer wavelengths than visible light.
  17. How does increasing temperature affect the resistance of a metal wire?
    Answer: Resistance increases because atoms vibrate more, obstructing electron flow.
    Example: Electric stove elements get more resistive when hot.
  18. What is the function of the coil in an electromagnet?
    Answer: It concentrates and strengthens the magnetic field when current flows.
    Example: Used in scrapyard cranes.
  19. Explain how a light ray changes direction when passing from air to glass.
    Answer: Light slows down entering the denser glass, bending towards the normal.
    Example: Glass lenses focus light in cameras.
  20. Why is mercury used in thermometers?
    Answer: It has a high boiling point and expands uniformly with temperature.
    Example: Mercury thermometers measure body temperature.

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📄 Page: 9