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Photoelectric Effect and WaveParticle Duality — Physics STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 SciencePhysicsPhotoelectric Effect and WaveParticle Duality3 Marks
Question
A 100W light bulb is placed at the centre of a spherical chamber of radius 20cm. Assume that 60% of the energy supplied to the bulb is converted into light and that the surface of the chamber is perfectly absorbing. Find the pressure exerted by the light on the surface of the chamber.
✓

Answer

Power = 100W Radius = 20cm 60% is converted to light = 60wNow, $\text{Force}=\frac{\text{power}}{\text{velocity}}=\frac{60}{3\times10^8}=2\times10^{-7}\text{N}.$
$\text{pressure}=\frac{\text{force}}{\text{area}}=\frac{2\times10^{-7}}{4\times3.14\times(0.2)^2}$
$\frac{1}{8\times3.14}\times10^{-5}$
$=0.039\times10^{-5}=3.9\times10^{-7}=4\times10^{-7}\text{N/m}^2.$

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