Solveeit Logo
Login

Question

Question: A 100 W sodium lamp radiates energy uniformly in all direction. The lamp is located at the centre of...

A 100 W sodium lamp radiates energy uniformly in all direction. The lamp is located at the centre of a large sphere that absorbs all the sodium light which is 589 nm

The number of photons delivered per second to the sphere is

A

3×10153 \times 10^{15}

B

3×10103 \times 10^{10}

C

3×10203 \times 10^{20}

D

3×10193 \times 10^{19}

Answer

3×10203 \times 10^{20}

Explanation

Solution

: Here, λ=589×10−9m,h=6.63×10−34js\lambda = 589 \times 10^{- 9}m,h = 6.63 \times 10^{- 34}js

p=100Wp = 100W

Energy of a photon

E=hcλ=6.63×10−34×3×108589×10−9j=3.38×10−19jE = \frac{hc}{\lambda} = \frac{6.63 \times 10^{- 34} \times 3 \times 10^{8}}{589 \times 10^{- 9}}j = 3.38 \times 10^{- 19}j

Number of photons delivered per second

n=pE=1003.38×10−19=3×1020n = \frac{p}{E} = \frac{100}{3.38 \times 10^{- 19}} = 3 \times 10^{20}Photons per seconds