Results

Using

s = ut + ½ at2

For the magnet falling to the first coil, where t is the time taken to reach the first coil.

0.145 = 0 + ½ at12

For the magnet falling from the start position to the second coil, where t again is the time taken to reach the first coil.

0.675 = 0 + ½ a(0.2026 + t)2

Solving the two equations for ‘a’ will arrive at a value for the acceleration due to gravity (g).

a = 9.5 m/s2

Answers to questions

  1. Was the value for ‘g’ the value you expected. If not, can you think why the value for ‘g’ is less or greater than what you expected.
    • Air resistance will impede the magnet as it falls
    • The induced emf represents electrical energy — this cannot have been created out of nothing — it is obtained at the expense of the magnets kinetic energy.
    • Lenz’s law is another way of looking at thesame thing — the induced emf always oposses the motion of the magnet — thereby slowing it down.