A Laser light of wavelength 660 nm is used to weld Retina detachment. If a Laser pulse of width 60 ms and power 0.5 kW is used the approximate number of photons in the pulse are: [Take Planck’s constant h = 6.62 × 10-34 Js]

Question

A Laser light of wavelength 660 nm is used to weld Retina detachment. If a Laser pulse of width 60 ms and power 0.5 kW is used the approximate number of photons in the pulse are: [Take Planck’s constant h = 6.62 × 10-34 Js] (A) 1020 (B) 1018 (C) 1022 (D) 1019

Tardigrade Admin · Accepted Answer

P=(nhc/λ t) n=(pλ t/hc) =5×103× (660× 10-9× 60× 10-3/6.6× 10-34× 3× 108) =100× 1018=1020

Q. A Laser light of wavelength $660 nm$ is used to weld Retina detachment. If a Laser pulse of width $60 m s$ and power $0.5 kW$ is used the approximate number of photons in the pulse are :
[Take Planck’s constant $h = 6.62 \times 1 0^{- 34} J s$ ]

$1 0^{20}$

$1 0^{18}$

$1 0^{22}$

$1 0^{19}$

$P = \frac{nh c}{λ t} n = \frac{p λ t}{h c}$
$= 5 \times 1 0^{3} \times \frac{660 \times 1 0 ^{- 9} \times 60 \times 1 0 ^{- 3}}{6.6 \times 1 0 ^{- 34} \times 3 \times 1 0 ^{8}}$
$= 100 \times 1 0^{18} = 1 0^{20}$

Q. A Laser light of wavelength 660nm is used to weld Retina detachment. If a Laser pulse of width 60ms and power 0.5kW is used the approximate number of photons in the pulse are : [Take Planck’s constant h=6.62×10−34Js]

1020

1018

1022

1019