  A fraction of energy is theoretically predicted to be captured from
electromagnetic field to form a gravitating mass, when a low-mass charged
particle enters the strong field from a region of no electromagnetism. In this
paper the mass variation has been calculated for a charged particle on
free-fall in the constraint electromagnetic field. It has been shown that there
is an evident effect to the variation in mass when the low-mass charged
particle is in the strong field.
