일반물리학 2 — Magnetic Fields Due to Currents: Problem 33

33 A long solenoid has 123 turns/cm and carries current \( i \). An electron moves within the solenoid in a circle of radius 2.30 cm perpendicular to the solenoid axis. The speed of the electron is 0.0187c (c = speed of light). Find the current \( i \) in the solenoid.