Question
Asked Dec 8, 2019
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How many photons are there in a 7.00 mJ laser beam of wavelength 785 nm?

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Expert Answer

Step 1

Energy is converted to joules as shown below:

1 mJ = 10-3 J

7mJ  = 0.007 J

The relation between number of photons, wavelength and energy is shown below:

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nhc E, (1)

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Step 2

Wavelength is converted int...

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1 nm =10° m 785 nm = 785×10-°m

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Atomic structure

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