Calculating Magnetic Force on a Lightning Rod: Homework Question [Answer Inside]

[Workout]

Homework Statement

Lightning strikes a lightning rod that is a thin, hollow cylinder with a radius of 1.0 cm with a peak current of 250 kA.
What is the magnetic force on an infinitesimal segment (vertical line) of current of width dx and
length L? [3]

Homework Equations

F = I[integral](dl)xB

The Attempt at a Solution

I calculated the magnetic field strength of B = 5.01 T
I'm not really sure how to start this? How do I incorporate the width dx?

 

[mfb]

How do I incorporate the width dx?

You get the current if you multiply the current density by dx.