Which of the following is not a unit of permeability?

$A$ bar magnet falls from rest under gravity through the centre of a horizontal ring of conducting wire as shown in figure. Which of the following graph best represents the speed $(v)$ vs. time $(t)$ graph of the bar magnet?

$A$ small bar magnet is moved through a coil at a constant speed from one end to the other. Which of the following series of observations will be seen on the galvanometer $G$ attached across the coil? Three positions shown describe: $(a)$ the magnet's entry,$(b)$ the magnet is completely inside,and $(c)$ the magnet's exit.

$A$ coil is placed in a time-varying magnetic field. If the number of turns in the coil were to be halved and the radius of the wire doubled,the electrical power dissipated due to the current induced in the coil would be: (Assume the coil to be short-circuited.)

When a coil is placed in a time-dependent magnetic field, the power dissipated in it is $P$. The number of turns, area of the coil, and radius of the coil wire are $N, A$, and $r$ respectively. For a second coil, the number of turns, area, and radius are $2N, 2A$, and $3r$ respectively. When the first coil is replaced with the second coil, the power dissipated in it is $\alpha P$. The value of $\alpha$ is . . . . . . .

$A$ metallic ring with a small cut is held horizontally and a magnet is allowed to fall vertically through the ring. Then the acceleration of the magnet is: