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AP® Physics C: E & M

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Moderate

Charge in B-field at an Angle

APPHEM-3CTZLJ

A particle of charge q, mass m, and speed v enters a uniform magnetic field of magnitude B that is directed down the page as shown.

If the particle enters the field at a 30-degree​ angle as shown, what is the radius of the circular path the particle makes?

A

0

B

$\mathit{\cfrac{qBr}{2m}}$

C

$\mathit{\cfrac{qBr}{m}}$

D

$\mathit{\cfrac{2qBr}{m}}$

E

$\mathit{\cfrac{\sqrt3 qBr}{2m}}$