How large is a photon?

Answer 1

Though it may be imprecise, when people refer to the size of a photon, they are talking about the wavelength associated with it. Seen in this way, the photons detected by the human eye are 4000 to 7000 angstroms (an angstrom is 1x10-10 meters). Numbers and measurements on such a scale are hard to imagine, but by comparison, a helium atom is about 1 angstrom, and the largest atoms are about 7. UV photons, X-rays, and gamma rays are smaller. Wavelengths of radio frequency photons can be very big, ranging from a millimeter to many kilometers.

Answer 2

There are two types of beta particles, β + and β -. β - are electrons, while β + are positrons (their antiparticles). The approximate radius of an electron is calculated as follows:

re = e2/(mec2) = 2.8179402894(58) cm -13

Positron are similar to electron in terms of size and mass.

Answer 3

The most recent work suggests a radius of 0.84087(39) fm, where (39) is the uncertainty in the last two numbers. There is some disagreement on the precise radius at this point; two different means to measure it come up with (slightly) different results.

Answer 4

Photons are considered elementary particles without rest mass.

photons have NO MASS

Answer 5

The photon has no mass so therefore it is dimensionless.

Answer 6

Smaller than the parts of an atom. Scientists can PREDICT the width of a single photon, but there is no way to actually measure a single photon.

Answer 7

Gamma rays haven't mass and dimension.