Physics 3 — Electricity & Magnetism

Magnetic force — only on the moving

continues from lesson 2 — values defined earlier in the course stay live here

A magnetic field does nothing to a parked charge. Move, and it pushes sideways — perpendicular to both v and B: F = q·v·B. Sideways force means circles, which is how mass spectrometers and old TVs steer beams:

q_{p} = 1.6 \cdot 10^{-19}

one proton (C)

v_{p} = 2000000

speed (m/s)

B_{1} = 0.5

field (T) — a strong lab magnet

F_{m} = q_{p} \cdot v_{p} \cdot B_{1}

1.6 \times 10^{-13}

sideways force (N)

r_{circ} = \frac{1.67 \cdot 10^{-27} \cdot v_{p}}{q_{p} \cdot B_{1}}

0.0418

radius of the proton's circle (m): r = mv/qB