Protons of speed 4×10⁵ m/s enter B=0.3 T at 60° to B. Find the helix pitch in mm, rounded to the nearest integer.
Physics · Magnetic effect of current
JEE Mains

Question

Protons of speed 4×10⁵ m/s enter B=0.3 T at 60° to B. Find the helix pitch in mm, rounded to the nearest integer.

G1 Physics · Accepted Answer

Helix pitch p=v∥T=(4×10⁵ cos 60°)[2πmₚ/(eB)]. Substitution gives p≈0.0437 m=43.7 mm, which rounds to 44.