An incandescent lamp is operated so that the tungsten filament initially reaches a…
PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Modern Physics · Modern Physics
Problem
An incandescent lamp is operated so that the tungsten filament initially reaches a steady-state temperature of T0=2500K. Engineers wish to know how the spectral distribution shifts when the filament temperature is increased by 5.0 % while the lamp is dimmed or brightened.
(a) Determine the peak emission wavelength of the filament at its initial temperature T0. Express your answer in nanometers.
(b) Without calculating the new absolute temperature, compute the percentage change in the peak wavelength that results from a 5.0 % increase in the filament’s temperature. Show your reasoning algebraically before substituting numbers.
(c) Using your answers to parts (a) and (b), determine the new numerical value of the peak wavelength after the temperature increase.
(d) Explain qualitatively how the change you found in part (c) would affect the apparent color of the lamp’s light as perceived by a human observer.