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Chapter 38: Q 38 (page 1115)

The wavelengths of light emitted by a firefly span the visible spectrum but have maximum intensity near 550 nm. A typical flash lasts for 100 ms and has a power output of 1.2 mW. How many photons does a firefly emit in one flash if we assume that all light is emitted at the peak intensity wavelength of 550 nm?

Short Answer

Expert verified

Number of photons emitted are3.32×1014.

Step by step solution

01

Step 1. Given information is :Maximum intensity of Light - 550 nmFlash lasts for 100 ms and Power output = 1.2 mW 

We need to find out the numbers of photons that the firefly emits in one flash.

02

Step 2. Using the definition of Power.

P=EnettEnet=NEphotonEphoton=hcλP=NhcλtN=PλthcN=1.2×10-3W550×10-9m100×10-3s6.63×10-343×108m/sN=3.32×1014

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