Physics · 2019
JEE Main · 10 April 2019, Shift 2 · Q24
A 2 mW laser operates at a wavelength of 500 nm. The number of photons that will be emitted per second is: [Given Planck's constant h =6.6 × 10^-34…
A $\displaystyle 2$ mW laser operates at a wavelength of $\displaystyle 500$ nm. The number of photons that will be emitted per second is :
[Given Planck's constant $\displaystyle \mathrm{h}=6.6 \times 10^{-34}$ Js, speed of light $\displaystyle \mathrm{c}=3.0 \times 10^8 \mathrm{~m} / \mathrm{s}$ ]
Official answer
(1)
$\displaystyle 5 \times 10^{15}$
More from Dual Nature of Matter and Radiation
- The electric field at a point associated with a light wave is given by E=200[ sin (6 × 10^15) t+ sin (9 × 10^15) t] Vm^-1 Given: h=4.14 × 10^-15 eVs…2022
- In photoelectric effect, the stopping potential (V_0) v / s frequency (ν) curve is plotted. ( h is the Planck's constant and φ_0 is work function of…2025
- The work functions of Aluminium and Gold are 4.1 eV and and 5.1 eV respectively. The ratio of the slope of the stopping potential versus frequency…2023
- An electron is released from rest near an infinite non-conducting sheet of uniform charge density ' -σ '.The rate of change of de-Broglie wave length…2025
- The work functions of cesium (Cs) and lithium (Li) metals are 1.9 eV and 2.5 eV, respectively. If we incident a light of wavelength 550 nm on these…2025
- The speed of electrons in a scanning electron microscope is 1 × 10^7 ms^-1. If the protons having the same speed are used instead of electrons, then…2021
- In photoelectric experiment energy of 2.48 eV irradiates a photo sensitive material. The stopping potential was measured to be 0.5 V. Work function…2024
- A particle having electric charge 3 × 10^-19 C and mass 6 × 10^-27 kg is accelerated by applying an electric potential of 1.21 V. Wavelength of the…2026
JEE Main 2019 Physics question, with the answer from NTA’s final answer key. Where our answers come from.