Question

Visible light is 400 – 700 nm. What part of the spectrum is this light bulb producing most of its light?

Since the peak isn’t visible light, why do you see it glowing? (A graph may help here.)

Answer 1

given
visible light spectrum = 400 - 700 nm

now a light bulb using a filament actually produces the most of its EM radiation in infrared part of the spectrum. As this peak is of intensity vs wavelenght is not in visible portion of the EM spectrum, still we see the bulb glowing
this is because the bulb , even though might be producing its maximum intensity at some different wavelength, as the same time it is producing other nearby wavelengths in lesser intensities as well and hence some part of this radiation falls under visible spectrum of the light and hence we c an see the light bulb glowing