Uniformo

Meet Uniformo, a little charge who feels exactly the same push everywhere between two plates.

Connect two large flat metal plates to a battery and one becomes positive while the other becomes negative. Between them the electric field points from the positive plate to the negative plate, and away from the edges it has the same strength and direction at every point. Physicists call this a uniform field.

Its strength is the voltage divided by the gap, E = V/d. A 12 V battery across plates 2 mm apart gives E = 12 / 0.002 = 6000 V/m. An electron placed anywhere in the middle feels the same force, eE ≈ 1.6 × 10⁻¹⁹ × 6000 ≈ 9.6 × 10⁻¹⁶ N.

Because the force is constant, a charge between the plates accelerates steadily, just like a ball falling in uniform gravity.

This simple setup is the heart of the capacitor and of old cathode ray tubes, which used pairs of plates to steer beams of electrons.