Question

P and Q are two identical charged particles each of mass 4 × 10^–26 kg and charge 4.8 × 10^–19 C, each moving with the same speed of 2.4 × 10⁵ m/s as shown in the figure. The two particles are equidistant (0.5 m) from the vertical Y-axis. At some instant, a magnetic field B is switched on so that the two particles undergo head-on collision.

Find –

1. the direction of the magnetic field and
2. the magnitude of the magnetic field applied in the region.

Answer 1

1. The direction of the magnetic field is perpendicular and inward into the plane.
2. For a head-on collision to take place, the radius of the path of each ion should be equal to 0.5 m.
   `r = (mv)/(qB)` = 0.5 m
   `B = (mv)/(qr) = (4 xx 10^-26 xx 2.4 xx 10^5)/(4.8 xx 10^-19 xx 0.5)`
   B = 0.04 T