# the number of photons emitted per second by the laser? (Plank’s constant Light of wave length 6730 Å is emitted by a He-Ne laser with output power of 2.3 mW. Calculate h = 6.63 × [10]^(-34) J)

##### 1 Answer

#### Answer

#### Answer:

#### Explanation

#### Explanation:

The intensity or power output of a laser (

Therefore, by rearranging:

Since we don't have frequency but rather wavelength, we can use

One further rearrangement, though you could use the above form:

We need to get everything into the correct units before we apply the equation.

The power output is

The wavelength must be in metres not Ångströms and since

So finally,

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