A-Level H2 Physics 6 — Questions and Answers
Question 1: What is nuclear binding energy?
- The energy needed to ionise an atom
- The energy required to completely separate a nucleus into its constituent protons and neutrons (Correct answer)
- The energy released in fission only
- The energy of the electrons in an atom
Correct answer: The energy required to completely separate a nucleus into its constituent protons and neutrons
Nuclear binding energy is the energy required to completely separate a nucleus into its individual protons and neutrons (nucleons). It equals the mass defect × c² (E=mc²).
Question 2: What is the difference between fission and fusion?
- Both split atoms
- Fission splits heavy nuclei; fusion combines light nuclei to release energy (Correct answer)
- Fusion splits atoms; fission combines them
- Both only occur in stars
Correct answer: Fission splits heavy nuclei; fusion combines light nuclei to release energy
Nuclear fission splits heavy nuclei (e.g., uranium-235) into smaller fragments, releasing energy. Nuclear fusion combines light nuclei (e.g., hydrogen isotopes) to form heavier nuclei, releasing even more energy per nucleon.
Question 3: What is meant by 'resonance' in mechanical systems?
- When damping is maximum
- When the driving frequency equals the natural frequency, producing maximum amplitude oscillations (Correct answer)
- When a system is at rest
- When energy is lost rapidly
Correct answer: When the driving frequency equals the natural frequency, producing maximum amplitude oscillations
Resonance occurs when the driving frequency matches the natural frequency of the system. At resonance, amplitude is maximum (limited only by damping) as energy is efficiently transferred to the system.
Question 4: What does 'Lenz's Law' state?
- The induced EMF is proportional to the rate of change of flux
- The induced current is in such a direction that its magnetic effect opposes the change causing it (Correct answer)
- A changing electric field produces a magnetic field
- EMF = BAv
Correct answer: The induced current is in such a direction that its magnetic effect opposes the change causing it
Lenz's Law states that the direction of the induced current is such that it opposes the change in flux that produced it — a consequence of conservation of energy.
Question 5: What is the condition for a particle to undergo uniform circular motion?
- No force acts on it
- A centripetal force acts towards the centre, changing direction but not speed (Correct answer)
- A tangential force acts on it
- Both centripetal and tangential forces act on it
Correct answer: A centripetal force acts towards the centre, changing direction but not speed
For uniform circular motion, a centripetal force directed toward the centre is required. It changes the direction of velocity (not speed), causing circular motion. F_c = mv²/r = mω²r.
Question 6: What is the principle behind a mass spectrometer?
- Separating isotopes by their boiling points
- Ionising atoms and separating them by mass-to-charge ratio using electric and magnetic fields (Correct answer)
- Measuring the speed of light
- Detecting radiation from unstable nuclei
Correct answer: Ionising atoms and separating them by mass-to-charge ratio using electric and magnetic fields
A mass spectrometer ionises atoms, accelerates them through an electric field, and uses a magnetic field to deflect them. Heavier ions deflect less — ions are separated by their mass-to-charge (m/q) ratio.
A-Level H2 Physics 6
What is nuclear binding energy?