Focal length of electrostatic lens

The kinematics of the 2nd part is getting too messy to solve and I'm getting an extra factor of e^(pi/2). What am I doing wrong?
WhatsApp_Image_2025-02-28_at_10.00.29_1f56e034.jpg
WhatsApp_Image_2025-02-28_at_10.00.29_b5381370.jpg
Was this page helpful?