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JEE Main 20211 SeptemberEvening Shift
Exam
JEE Main
Year
2021
Date
1 September
Shift
Evening Shift
Subject
Chemistry
Chapter
Structure of Atom

JEE Main 2021 · 1 September · Evening Shift · Chemistry · Structure of Atom

A 50 watt bulb emits monochromatic red light of wavelength of 795nm...

A 5050 watt bulb emits monochromatic red light of wavelength of 795nm795nm. The number of photons emitted per second by the bulb is x×1020.x \times {10}^{20} . The value of xx is _____ .

(Nearest integer)

[Given :\lefth=6.63×10−34Jsandc=3.0×108ms−1]\text{[Given :}\lefth = 6 . 63 \times {10}^{- 34}Js\text{and}c = 3 . 0 \times {10}^{8}{ms}^{- 1}]

Correct answer

0

Step-by-step solution

Power=50J/sec.time=1sec.So,E=50J\text{Power} = 50J / sec . time = 1sec . So, E = 50J

E=n[hcλ]E = n\left[\dfrac{hc}{\lambda}\right]

n=[50×795×10−96.63×10−34×3×108]=1998.5×1017≅2×1020n = \left[\dfrac{50 \times 795 \times {10}^{- 9}}{6 . 63 \times {10}^{- 34} \times 3 \times {10}^{8}}\right] = 1998 . 5 \times {10}^{17} ≅ 2 \times {10}^{20}

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