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⚛️ Physics  ·  Moving Charges and Magnetism  ·  NEET & JEE

A proton moves perpendicular to B=0.1 T field at 10<sup>6</sup> m/s. Radius of circular path (m<sub>p</sub> = 1.67 x 10<sup>-27</sup> kg, e = 1.6 x 10<sup>-19</sup> C):

Answer: 0.104 m.

  • A 0.104 m
  • B 1.04 m
  • C 10.4 m
  • D 0.01 m

Correct answer: A. 0.104 m

Explanation: r = mv/(qB) = 1.67x10<sup>-27</sup> x 10<sup>6</sup> / (1.6x10<sup>-19</sup> x 0.1) = 1.67x10<sup>-21</sup> / 1.6x10<sup>-20</sup> = 0.104 m.

Magnetic Field Lines Around a Straight WireIfield forms concentric circles around the wire (right-hand rule)

The magnetic field around a long straight current-carrying wire forms concentric circles, with direction given by the right-hand rule (point thumb along I, fingers curl in the direction of B).

Concept context

Magnetic force on moving charges and currents, the Biot-Savart law, Ampere's law, and the cyclotron - how electric currents create and respond to magnetic fields.

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