'********************************************************
'* Calculate relativistic mass and speed of an electron *
'* accelerated in an electron gun                       *
'* ---------------------------------------------------- *
'* SAMPLE RUN:                                          *
'*                                                      *
'* Give electron gun voltage in volts: 1E6              *
'*                                                      *
'* Relativistic mass (kg) and speed (m/s):              *
'*  2.693394E-30  2.8212498E+08                         *
'*                                                      *
'* ---------------------------------------------------- *
'* Ref.: "Problem Solving with Fortran 90 By David R.   * 
'*        Brooks, Springer-Verlag New York, 1997".      *
'*                                                      *
'*                 Basic Release By J-P Moreau, Paris.  *
'*                          (www.jpmoreau.fr)           *
'********************************************************
' Explanations:
' ------------
'
'  An electron accelerated by a voltage V in an electron gun
'
'                               2     2
'  acquires an energy of Ve = mc - m c,  where
'                                   0
'                                         -19
'   charge on an electron   e = 1.602 x 10    coulomb
'
'                                          -31
'   rest mass               m  = 9.109 x 10    kg
'                            0
'                                          8
'   speed of light          c = 2.9979 x 10  m/s
'
'  The speed v of an electron of relativistic mass m (kg) is
'  obtained from
'                                           2
'                  m/m  = 1 / sqrt(1 - (v/c) )
'                     0
'
'----------------------------------------------------------
'  restmass, relamass,          ( kg )
'  voltage,                     ( volt )
'  speed,                       ( m/s )
'  e,                           ( electron charge in coulomb )
'  c: double;                   ( speed of light in m/s )

  e = 1.602E-19: c = 2.9979E+08: restmass = 9.109E-31

  CLS
  PRINT
  INPUT " Give electron gun voltage in volts: ", voltage

  relamass = (voltage * e + restmass * c * c) / (c * c)

  speed = c * SQR(1! - (restmass / relamass) ^ 2)

  PRINT
  PRINT " Relativistic mass (kg) and speed (m/s):"
  PRINT " "; relamass; " "; speed
  PRINT

END

' End of file rel_mass.bas