# Faraday and Lenz's Law - Coil Experiment

I have conducted an experiment with a magnet, 2 distinct coils (800/1600 solenoids) and a galvanometer to measure the electric current produced by the magnetic flux.

I'm having some issues understanding/relating the concepts observed with Faraday's and Lenz's law:

• I connected a led to the circuit, observing that it only turned on when I inserted the magnet in the coil facing a certain direction (positive pole of the magnet + positive pole of the coil). However, testing this same effect in an online simulator, I see that the led should have turned on whichever way I inserted the magnet. Did I setup my preparation improperly?
• In the 1600 solenoid coil, I noticed that I needed to move the magnet with much less speed for the led to turn on (and with more intensity), in comparison to the 800 solenoid coil. I measured that for the led to turn on, I needed 40 mV / 15 uA of tension using the 800 solenoid coil, but 60 mV / 20 uA using the 1600 solenoid coil.

Regarding Faraday's law formula: R . I = -N d ψ/ dt

Knowing the Resistance (R) of the 800 solenoid coil is 32.2Ω, and the resistance of the 1600 solenoid coil is 64.0Ω, is the difference in the resistance values the reason for the difference in necessary tension?

• With the measured "necessary tension" values for both coils, can I theorically calculate the minimum tension value for it to come on without having measured the magnetic flux (d ψ/ dt)? I know that the reference value for the led is 1.68V.