
Spring 2011 

Exercise: Light & Energy 


Discussion Modules 


Speed of light in vacuo = c = 2.9979 x 10^{8}m/s 
c = f• 
Plank's constant = h = 6.626 x 10^{34}J*s 
E_{photon} = hf = hc/ 
J = kg m^{2}s^{2} 
= h/mv 
E= mc^{2} 
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 ^{12}C atom moving at 2 m/sec.
In addition to these exercises you should familiarize yourself with the text materials referenced below.
© R A Paselk
Last modified 10 March 2009