So, 2 times pi times the radius.

因此，2 倍 pi 乘以半径。

The surface area of a sphere is equal to (4) times (pi) times (its radius squared).

球体的表面积 等于 (4) 乘以 (pi) 乘以（其半径的平方）。

We also know the Coulomb constant equals the  inverse of the quantity four pi times the permittivity of free space.

我们还知道库仑常数等于四圆周率乘以自由空间介电常数的倒数。

In this case, the frequency will also be equal to 1 over (2 pi) times (the square root of k) over (m).

在这种情况下，频率也等于 1 乘以 2 pi 乘以 k 乘以 m 的平方根。

And all of a sudden, this becomes a very clean-- we just say 2 pi times our variance, times e to the number of standard deviations we are away from the mean.

突然间，这变得非常干净——我们只是说 2 pi 乘以我们的方差， 乘以 e 到我们远离均值的标准差数。