The lateral area of a cylinder is the area on the outside, meaning if you would cut open a cylinder longitudinally, and folded it open, the rectangle that remains is the lateral area of the cylinder.
The formula for the lateral area of a cylinder is:
Where 2πr represents one side of the rectangle, and h represents the other.
We know (Ohm second law) that where k inlcudes the rest of the parameters (material, lenght). In our situation we have k= . The moment the diameter becomes 8mm R becomes
