What is the de Broglie wavelength of an electron moving with a kinetic energy of 100 eV? (mass of electron = 9.1 x 10⁻³¹ kg, h = 6.626 x 10⁻³⁴ Js)
Correct: A
Kinetic energy (KE) = 100 eV = 100 * 1.6 x 10⁻¹⁹ J. KE = 1/2 mv², so v = √(2KE/m) = √(2 * 100 * 1.6 x 10⁻¹⁹ / 9.1 x 10⁻³¹) = 5.93 x 10⁶ m/s. De Broglie wavelength λ = h/mv = 6.626 x 10⁻³⁴ / (9.1 x 10⁻³¹ * 5.93 x 10⁶) = 1.23 x 10⁻¹⁰ m = 1.23 Å.