20150918

Physics quiz question: first radiation constant

Physics 205A Quiz 1, fall semester 2015
Cuesta College, San Luis Obispo, CA

The first radiation constant c1 is given by the expression[*]:

c1 = 2πh·c2.

The Planck constant h is measured in units of kg·m2·s–1, and the speed of light c is measured in units of m·s–1. The units for the first radiation constant c1 are:
(A) kg2·m5·s–3.
(B) kg1/2·m2·s–3/2.
(C) kg·m3·s–2.
(D) kg·m4·s–3.

[*] goldbook.iupac.org/R05051.html.

Correct answer (highlight to unhide): (D)

Replacing the quantities in the equation for the first radiation constant with their kg, m and s units (while also ignoring the 2π term, as it is unitless); the units of c1 are:

c1 = kg·m2·s–1·(m·s–1)2,

c1 = kg·m2·s–1·m2·s–2,

c1 = kg·m4·s–3.

Sections 70854, 70855, 73320
Exam code: quiz01rdBL
(A) : 2 students
(B) : 1 student
(C) : 15 students
(D) : 62 students

Success level: 78%
Discrimination index (Aubrecht & Aubrecht, 1983): 0.41

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