I can only guess that wind turbines used to generate electricity have only 3 blades because it is the most efficient design.
If this is the most efficient design, then why do house fans have more blades. Why are they not made with 3 blades?

(may be broke/outdated!)
I can only guess that wind turbines used to generate electricity have only 3 blades because it is the most efficient design.
If this is the most efficient design, then why do house fans have more blades. Why are they not made with 3 blades?