Humboldt State University ® Department of Chemistry

Richard A. Paselk


General Chemistry

Spring 2011

Exercise: Light & Energy

© R. Paselk 2008

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Light and Energy

Speed of light in vacuo = c = 2.9979 x 108m/s
c = f• lambda
Plank's constant = h = 6.626 x 10-34J*s
Ephoton = hf = hc/ lambda
J = kg m2s-2
lambda= h/mv
E= mc2

1. What is the frequency of light with a wavelength of 650.4 nm?


2. What is the wavelength of a photon which has a frequency of 90.50 MHz?


3. KHSU broadcasts at 90.50 MHz.

a. Find the energy of one KHSU photon.

b. If KHSU has a 9,000 watt transmitter how many photons does it release each second (one watt = one J/sec)

4. Find the wavelength of a 12C atom moving at 2 m/sec.


Answers 1-4

In addition to these exercises you should familiarize yourself with the text materials referenced below.

Go to Reflection Questions

© R A Paselk

Last modified 10 March 2009