The magnitude of the induced emf is proportional to the rate of change of flux linking a circuit.
E r d£ dt
E emf, magnetic flux, t time Lenz’s law
The direction of the induced emf is always such as to oppose the change causing it. Modern Physics
Einstein’s photoelectric law The energy of the fastest electron emitted is the difference between the energy of the photon and the work function of the metal.
hf £ 1 2mv max
2
h Planck’s constant, f frequency of the EM wave, work function of the metal, m mass of an electron, vmax maximum velocity of any of the emitted electrons
Law of radioactive decay
The activity of a radioactive source is proportional to the number of undecayed nuclei present. A N
l
A activity, the decay constant for the particular isotope, N the number of undecayed nuclei l
