How much is a bullet deflected by the Earth's Magnetic Field?A 3.8g bullet is moving at 180m/s in the Earth's 5x10-5T field. If the bullet has a charge of 8.1x10-9C, by what distance will it be deflected after it has travelled 100m?
The magnitude of the force on the bullet at any time is given by the Lorentz force law:
As this acceleration is very small it leads to a negligible change in velocity â€“ so weâ€™ll approximate the 100m as being in the original direction of travel and the force as being constant, due to a constant velocity of 180m/s.
The time taken to cross 100m is:
In this time, the sideways pushing magnetic force will lead to a small sideways deflection, x: