Question

Why is it more difficult to move a magnet towards a coil which has a large number of turns ?

Answer 1

Lenz's law states that when an emf is generated by a change in magnetic flux according to Faraday's Law, the polarity of the induced emf is such, that it produces an current that's magnetic field opposes the change which produces it.
The negative sign used in Faradays law of electromagnetic induction, indicates that the induced emf $\left(\epsilon \right)$ and the change in magnetic flux $\left(\delta \varphi B\right)$ have opposite signs.
$\epsilon =-N\frac{\delta \varphi B}{\delta t}$
Where,
$\left(\epsilon \right)$ = Induced emf
$\left(\delta \varphi B\right)$= change in magnetic flux
N = No of turns in coil
Hence, the e.m.f. induced in the coil becomes more when the numbers of turns in the coil are made large and the increased induced e.m.f. opposes the cause with a greater force which produces it.