$1-$ Why do we use gear box?

$2-$ Why the deviation in wind direction is controlled in wind turbines, and how it is controlled?

$3-$ What is Betz limit$?$

$4-$ provide a short description about the largest wind turbines that exist $($operating$)$ nowadays supported by a reference.

$5-$ Why do you think stall can be considered a good thing in wind turbines?

$6-$ The amount of wind energy at $15C$ and $1-$atm pressure that passes through $1m^2$ of crosssectional area for $100$ h of $13\mathrm{.}4$ mph winds is:

a$.827$ Wh

b$.22,326Wh$

c$.13,230Wh$

d$.147,373\mathrm{.}87Wh$