Exercise 7 | Early Quantum Theory

Determine the De Broglie’s wavelength of a car (m = 3.00 x 103 lb) traveling at 55.0 mi.hour-1.

Data: 1 kg = 2.205 lb and 1 km = 0.6214 mi.

λ = h / p = h / mv


m = 3.00 x 103 lb × 1 kg2.205 lb =  1.36 x 103 kg


v = 55 mi1 hour × 1000 m0.6214 mi × 1 hour3600 s  = 24.6 m.s-1


λ = 6.626 × 10-341.36 × 103 × 24.6 = 1.98 x 10-35 m