Alaser pulse with wavelength 550 nm contains 4.40 mj of energy. how many photons are in the laser pulse?

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Solution:- First of we calculate the energy of the laser pulse for it's given wavelength which actually the energy in joule per photon. After this the given energy value is divided by the calculated energy to find out the number of photons.

The calculations are done as:

For energy calculations the equation used is:

where, E is energy, h is planck's constant and is the wavelength.

The values of the constants are as follows:

wavelength is given as 550 nm. We need to convert it to m.

Let's plug in the values in the equation to calculate E:

This is the energy for one photon. The given energy value is 4.40 mJ that is .

let's divide this value by the calculated value to get the number of photons as:

=

So, there would be photons in the laser pulse.

c is the answer because when something is left after something evaporates that shows the chemical change.

explanation: it gains negative electrons, therefore becoming negatively charged. as charge cannot be created, nor destroyed, only transferred, this leaves the wool positive. now that they have opposite charges, the two items attract.