Cobalt-60 is radioactive isotope used to treat cancers. A gamma ray photon emitted by this isotope has an energy of 2.13 x 10—13 J. What is the wavelength of this gamma ray in SI unit?

E = hc/wavelength.

This will give you wavelength in m if you plug h and c in with the correct units.

To find the wavelength of a gamma ray, you can use the equation:

wavelength (λ) = speed of light (c) / frequency (ν)

We can find the frequency by using the equation:

energy (E) = Planck's constant (h) * frequency (ν)

Rearranging the equation, we get:

frequency (ν) = energy (E) / Planck's constant (h)

The speed of light is a constant value, approximately equal to 3 x 10^8 meters per second (m/s), and Planck's constant is approximately equal to 6.63 x 10^-34 Joule-seconds (J·s).

Substituting the given energy value into the frequency equation, we get:

frequency (ν) = (2.13 x 10^-13 J) / (6.63 x 10^-34 J·s)

Simplifying, we have:

frequency (ν) ≈ 3.21 x 10^20 Hz

Now, we can substitute the speed of light and frequency into the wavelength equation to find the wavelength in meters:

wavelength (λ) = (3 x 10^8 m/s) / (3.21 x 10^20 Hz)

Simplifying, we have:

wavelength (λ) ≈ 9.34 x 10^-13 meters (or 9.34 picometers)

Therefore, the wavelength of the gamma ray emitted by cobalt-60 is approximately 9.34 x 10^-13 meters or 9.34 picometers.