no question please so what's the problem
Answer:
Radius, r = 0.00523 meters
Explanation:
It is given that,
Magnetic field, 
Current in the toroid, I = 9.6 A
Number of turns, N = 6
We need to find the radius of the toroid. The magnetic field at the center of the toroid is given by :

r = 0.00523 m
or

So, the radius of the toroid is 0.00523 meters. Hence, this is the required solution.
Every point on the surface must have the same rotational speed.
Otherwise some places would rotate away from other places.
If the next block of your city rotated faster than the block that you live on,
then you could sit at home, look out the window, and watch your school
rotate past your house.
The map of the continents on the Earth would change constantly.