The filament of a light bulb has surface area 64 mm The

Last updated: 6/24/2023

The filament of a light bulb has surface area 64 mm The filament can be considered as a black body at temperature 2500 K emitting radiation like a point source At night the light bulb is observed from a distance of 10 m Assume light detector to be circular with radius r 10 3 m Then Take o 5 67 x 10 Wm K Wien s displacement constant 2 90 x 10 m K Planck constant 6 63 x 10 Js speed of light in vacuum 3 00 x 10 m s assume detector absorbs all the radiation incident on it and point source filament lie on the axis of detector A Power radiated by the filament is in the range 642 W to 645 W B Radiated power entering into detector is in the range of 34 42 W tp 34 52 W The wavelength corresponding to the maximum intensity of light is 1160 nm D Taking the average wavelength of emitted radiation to be 1740 nm the total number of photons entering per second into detector is in the range 3 1 x 10 to 3 2 10