## 20160904

### Physics quiz question: Wien displacement constant units

Physics 205A Quiz 1, fall semester 2016
Cuesta College, San Luis Obispo, CA

The Wien displacement constant b is given by the expression[*]:

b￼ = h·c/k.

The Planck constant h is measured in units of kg·m2·s–1, the speed of light c is measured in units of m·s–1, and the Boltzmann constant k is measured in units of K–1·kg·m2·s–2. The units for the Wien displacement constant b are:
(A) K·m.
(B) K–1·s–1.
(C) K·kg·m–1.
(D) K–1·m4·s–4.

[*] wki.pe/Physical_constant#Physico-chemical_constants.

Correct answer (highlight to unhide): (A)

Starting with the expression for the Wien displacement constant b:

b￼ = h·c/k,

and replacing the quantities in the equation with their K, kg, m and s units, the units of b are:

b￼ = (kg·m2·s–1)·(m·s–1)/(K–1·kg·m2·s–2),

b￼ = (kg·m3·s–2)/(K–1·kg·m2·s–2),

b￼ = K·m.

Sections 70854, 70855, 73320
Exam code: quiz01bIR6
(A) : 53 students
(B) : 2 students
(C) : 0 students
(D) : 2 students

Success level: 93%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.15