DF: dimensionless quantity numerically equal to a change in the radiance temperature of the tungsten ribbon (in °C) under changes in the base temperature by 1 °C at constant lamp current
DF: dimensionless quantity numerically equal to a change in the radiance temperature of the tungsten ribbon (in °C) under changes in the base temperature by 1 °C at constant lamp current
DF: dimensionless quantity numerically equal to a change in the radiance temperature of the tungsten ribbon (in °C) under changes in the base temperature by 1 °C at constant lamp current