This Is a Certified Answer

Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
The magnetic force is horizontal and is 16 N. This gives the normal reaction force on magnet exerted by the board. 

Frictional force between board and magnet = μ N = μ 16 Newtons

Weight of magnet = 2 * 10 Newtons.

They are in equilibrium and hence the magnet is stationary.
 Hence   16 μ = 20    =>  μ = 1.25        ( it is very high because of magnetic effect)