NTA Abhyas JEE Main2020PhysicsMagnetic Effects of CurrentPractice
A charged particle enters a uniform magnetic field with a velocity vector at an angle of 45 ° with the magnetic field. The pitch of the helical path followed by the particle is p . The radius of the helix will be -
Options
- Ap 2 π
- B2 p
- Cp 2 π
- D2   p π
Correct answer
C. p 2 π
Step-by-step solution
Pitch of helical path is, p = v cos θ × 2 π m q B = 2 π m v cos 45 ° q B = 2 π m v 2 q B Also radius of helix is, r = m v sin θ q B = m v 2 q B ∴ r p = m v 2 q B × 2 q B 2 π m v = 1 2 π or r = p 2 π