Question

The number of photons emitted in 10 hours by a 60 W
sodium lamp (2 of photon=6000 A)
(a) 6.50 × 10^24
(b) 6.40 10^23
(c) 8.40 x 10^23
(d) 3.40 x 10^23​

Answer 1

$</strong><strong>ANSWER</strong><strong> \:$

Energy of photon, E = hν = h(c/λ) = 3.374 x 10-19 J

[It is known that, h = 6.626 x 10-34 m2 kg/s and c = 3 x 108 m/s]

Number of photons emitted by the sodium lamp in one second = [60 / 3.374 x 10-19]

∴ The number of photons emitted by the sodium lamp in 10 hours is

= [(60 x 10 x 3600)/ (3.374 x 10-19)] = 6.4 x 1024