A 160 W infrared source is radiating light of wavelength 50000 mathringA uniformly in all directions. The photon flux at a distance of 1.8 m is the order of

Question

A 160 W infrared source is radiating light of wavelength 50000 mathringA uniformly in all directions. The photon flux at a distance of 1.8 m is the order of (A) 10 m-2s-1 (B) 1010 m-2s-1 (C) 1015 m-2s-1 (D) 1020 m-2s-1

Tardigrade Admin · Accepted Answer

Total photons emitted from source is <img class="img-fluid question-image" alt="image" src="https://cdn.tardigrade.in/img/question/physics/3b911e12e70d0f4487440b80bb9e3ca5-.jpeg" /> N=( text Power /h c / λ)=(160 × 50000 × 10-10/6.6 × 10-34 × 3 × 108) So, photon flux falling over spherical surface of radius r=18 m is n =(N/A)=(N/4 π r2) =(160 × 50000 × 10-6/6.6 × 10-34 × 3 × 108 × 4 π ×(1.8)2) ≈ 1020 m -2 s -1

Q. A $160 W$ infrared source is radiating light of wavelength $50000 \overset{˚}{A}$ uniformly in all directions. The photon flux at a distance of $1.8 m$ is the order of

$10 m^{- 2} s^{- 1}$

$1 0^{10} m^{- 2} s^{- 1}$

$1 0^{15} m^{- 2} s^{- 1}$

$1 0^{20} m^{- 2} s^{- 1}$

Q. A 160W infrared source is radiating light of wavelength 50000A˚ uniformly in all directions. The photon flux at a distance of 1.8m is the order of

10m−2s−1

1010m−2s−1

1015m−2s−1

1020m−2s−1

Total photons emitted from source is N=hc/λ Power ​=6.6×10−34×3×108160×50000×10−10​ So, photon flux falling over spherical surface of radius r=18m is n=AN​=4πr2N​ =6.6×10−34×3×108×4π×(1.8)2160×50000×10−6​ ≈1020m−2s−1

Q. A $160 W$ infrared source is radiating light of wavelength $50000 \overset{˚}{A}$ uniformly in all directions. The photon flux at a distance of $1.8 m$ is the order of

$10 m^{- 2} s^{- 1}$

$1 0^{10} m^{- 2} s^{- 1}$

$1 0^{15} m^{- 2} s^{- 1}$

$1 0^{20} m^{- 2} s^{- 1}$