Questions:

1. Beginning from equation (1), show that the correct expression for the induced emf in a secondary coil, due to a sinusoidally varying current in a primary coil is
   
   $${\cal E} = \frac{\mu_o N_s N_p A_s V_0 2 \pi f}{l_s R} \cos{( 2 \pi f t)},$$
   
   
   for infinitely thin, long ($l \gg r$), concentric solenoids (primary surrounding the secondary). The subscripts s, p, and o, refer to the secondary, primary, and the voltage of the ac source in the primary circuit.
2. What do you expect should happen to the magnitude of the voltage across the coil as the frequency is increased? Explain. Do your result corroborate your suspicions? Display a graph of the calculated and measured secondary voltages as a function of frequency, and discuss its import.

3. State Lenz's law. How was this law apparent in this experiment?