What is the length of a box in which the minimum energy of an electron is 1.5*10^-18 J?

L=2*10^-10m

Explanation:

we need to evaluate for a minimum energy:

Planck constant = h = 6,62607015 * 10 - 34 kg⋅m2⋅s-1

1.5*10^-18J = 10eV

En = n^2h^2 / 8mL^2

for n=1 (minimum energy)

E1 = h^2 / 8mL^2

so ...

L^2 = h^2 / (8mE1)

L^2 = (6.63*10^-34) ^2 / [ 8 (9.11*10^-31) * (1.5*10^-18J) ]

L^2 = 4.02*10^-20

L = 2*10^-10 m