Question

What is the potential difference required to stop an electron traveling at an initial speed of 2.29 x 107 m/s? (mass of an electron is 9.1 X 10-31 kg)

Answer 1

E = mv² / 2 = 9.1 × 10^-31 × (2.29 × 10⁷)² / 2 = 2.39 × 10^-16 (J) = 2.39 × 10^-16 / 1,602 × 10⁻¹⁹ = 14.3 eV.

Answer: 14.3 eV.