paper 2 physics rn

• the primary coil is connected to an alternating voltage supply. explain how an emf is induced in the secondary coil (3)

  • there is a changing magnetic flux linkage in the primary coil
  • the iron core links the flux to the secondary coil
  • the changing magnetic flux linkage in the secondary coil induces an emf
  • faraday's law: emf induced is directly proportional to the rate of change of magnetic flux linkage
• control rods absorb neutrons without further fission
• moderator slows down neutrons
• • electrons are removed from plate X and deposited on plate Y
  • X becomes positive and Y becomes negative
  • equal number of electrons deposited
• describe the nature of the strong nuclear force

  • It acts between quarks / nucleons / hadrons
  • ‘Short-range’ force
  • Repulsive below (about) 0.5 fm
  • Attractive up to (about) 3 fm
• explain why high temperatures are necessary for fusion reactions otto occur in stars

  • The protons / nuclei repel each other
  • At high temperature particles have more KE and hence can get close enough to fuse
• velocity selector

  • Apply a magnetic field at right angles to electric field
  • electric force = magnetic force
  • No resultant vertical force, so only beta-particles with a specific speed will travel horizontally
  • EQ = BQv
• how a transducer produces and receives ultrasound waves

  • High frequency alternating PD applied to the faces of the piezoelectric crystal
  • Causes the piezoelectric crystal to stretch and compress / oscillate / resonate at high frequency
  • Ultrasound waves sent in pulses
  • Between pulses, reflected ultrasound incident on the piezoelectric crystal causes the crystal to change shape / oscillate / resonate
  • An alternating PD is induced
• gel

  • Acoustic impedance of air is different to body
  • Acoustic impedance of gel is similar to body
  • This allows greater transmission of the ultrasound waves into / out of the patient’s body
  • There is less reflection of the ultrasound waves at the body boundary
• explain why a greater signal is received back from B than C

  • Acoustic impedance of C is different from B
  • Change in acoustic impedance at B is greater
• binding energy per nucleon

  the minimum energy required to remove a nucleon from the nucleus