Question

In a ruby laser, total number of Cr^3- ions is 2.8*10^19. If the laser emits radiation of wavelength 7000A°. Calculate the energy of laser pulse.

Answer 1

Given-:

Total number of $Cr^3$- ions= $2.8\times 10^{19}$

Laser emits radiation of wavelength =7000A°.

To find-:

Energy of the laser pulse.

Solution-:

Here; we have:

Using formula-:

E=$\frac{hc}{\lambda}$

We know the values of:

Planck's constant i.e h=6.626 x $10^{-34}$J.s

Speed of light c=3 x $10^8$ m/s.

According to the question we have:

Wavelength $\lambda$= 7000A° = 7000 x $10^{-10}$ m.

Hence, by putting in the formula we get:

E=$\frac{(6.626 \times 10^{-34}J.s \times 3 \times 108 m/s)}{7000} \times 10^{-10m}$

By calculating we get:

E=$2.8 \times 10^{-19}$J.  

The energy of laser pulse=  $2.8 \times 10^{-19}$J.

Answer 2

Given-:

Total number of $Cr^3$- ions= $2.8\times 10^{19}$

The laser emits radiation of wavelength =7000A°.

To find-:

Energy of the laser pulse.

Solution-:

Here; we have:

Using formula-:

$E=\frac{hc}{\lambda}$

We know the values of:

Planck's constant i.e $h=6.626 \times J.s$

Speed of light $c=3 x m/s.$

According to the question we have:

Wavelength = 7000A° = 7000 x  m.

Hence, by putting in the formula we get:

$E=\frac{(6.626\times 10^{34}J.s \times 3\times 108m/s)}{7000}\times 10^{-10m}$

By calculating we get:

$E=2.8\times 10^{-19}J$

The energy of laser pulse$= 2.8\times 10^{19}J$.

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