Question

Gamma rays are photons with very high energy.

What is the wavelength of a gamma-ray photon with energy 625 keV ?

How many visible-light photons with a wavelength of 500 nm would you need to match the energy of this one gamma-ray photon?

Answer 1

1.

Energy of photon is given by,

E = h*c/

here, h = 6.63*10^-34

c = 3*10^8

given, E = 625 keV = (625*10^3)*(1.60*10^-19) J

E = 1*10^-13 J

So, = wavelength = h*c/E = (6.63*10^-34)*(3*10^8)/(1.0*10^-13)

= 1.99*10^-12 m

2.

Let take wavelength of visible light = 500 nm

then, energy of visible light = Ev = (6.63*10^-34)*(3*10^8)/(500*10^-9)

Ev = 3.97*10^-19 J = (3.97*10^-19)/(1.60*10^-19) eV

Ev = 2.48 eV

given, Energy of gamma photon = E = 625 keV = 625*10^3 eV

So, number of can be given by,

n = E/Ev

n = (625*10^3)/2.48

n = 2.52*10^5