Question

Be sure to answer all parts. Cobalt-60 is a radio active isotope used to treat cancers of the brain and other tissues. A gamma ray emitted by an atom of this isotope has an energy of 5.20 MeV (million electron volts; l eV 1.602 x 109 J. What is the frequency (in Hz) and the wavelength (in m) of this gamma ray? Enter your answers in scientific notation. Frequency: x 10 Hz Wavelength: x 10.

Answer 1

E = 5.20 MeV
= 5.20*10^6 eV
= 5.20*10^6 * 1.602*10^-19 J
= 8.33*10^-13 J

1)
Given:
E = 8.33*10^-13 J

use:
E = h*f
8.33*10^-13 J =(6.626*10^-34 J.s)*f
f = 1.257*10^21 Hz
Answer: 1.26*10^21 Hz

2)

use:
E = h*c/lambda
8.33*10^-13J =(6.626*10^-34 J.s)*(3.0*10^8 m/s)/lambda
lambda = 2.39*10^-13 m