JEE Mains · Physics · STD 12 - Dual nature of radiation and matter
- JEE Mains 2024
- Hard
- MCQ
Monochromatic light of frequency \(6 \times 10^{14} \mathrm{~Hz}\) is produced by a laser. The power emitted is \(2 \times 10^{-3} \mathrm{~W}\). How many photons per second on an average, are emitted by the source? (Given \(\mathrm{h}=6.63 \times 10^{-34} \mathrm{Js}\) )
Pick an option to check your answer.
Answer & Solution
Correct Answer
(C) \(5 \times 10^{15}\)
Step-by-step Solution
Detailed explanation
\(\mathrm{P}=\mathrm{nh \nu}\)
\(\mathrm{n}=\frac{\mathrm{P}}{\mathrm{h} \nu}=\frac{2 \times 10^{-3}}{6.63 \times 10^{-34} \times 6 \times 10^{14}}\)
\(=5 \times 10^{15}\)
More questions from Physics
- The moment of inertia of a uniform cylinder of length \(l\) and radius \(R\) about its perpendicular bisector is \(I\). What is the ratio \(l/R\) such that the moment of inertia is minimum?JEE Mains 2017 Hard
- The average kinetic energy of a molecule of the gas isJEE Mains 2023 Easy
- A concave mirror produces an image of an object such that the distance between the object and image is 20 cm . If the magnification of the image is ' -3 ', then the magnitude of the radius of curvature of the mirror is :JEE Mains 2025 Easy
- A metal plate of area \(1\times10^{-4}\, m^2\) is illuminated by a radiation of intensity \(16\, m\,W/m^2\). The work function of the metal is \(5\,eV\). The energy of the incident photons is \(10\, eV\) and only \(10\%\) of it produces photo electrons. The number of emitted photo electrons per second and their maximum energy, respectively, will be : \([1\, eV = 1.6\times10^{-19}\, J]\)JEE Mains 2019 Hard
- A simple pendulum is being used to determine the value of gravitational acceleration \(\mathrm{g}\) at a certain place. The length of the pendulum is \(25.0\; \mathrm{cm}\) and a stop watch with \(1\; \mathrm{s}\) resolution measures the time taken for \(40\) oscillations to be \(50\; s\). The accuracy in \(g\) is ....... \(\%\)JEE Mains 2020 Medium
- A parallel plate capacitor has charge \(5 \times 10^{-6} \mathrm{C}\). A dielectric slab is inserted between the plates and almost fills the space between the plates. If the induced charge on one face of the slab is \(4 \times 10^{-6} \mathrm{C}\) then the dielectric constant of the slab is ________.JEE Mains 2025 Medium
More PYQs from JEE Mains
- A plane electromagnetic wave of frequency \(35\ \mathrm{MHz}\) travels in free space along the \(\mathrm{X}\)-direction. At a particular point (in space and time) \(\overrightarrow{\mathrm{E}}=9.6\ \hat{\mathrm{j}} \mathrm{V} / \mathrm{m}\). The value of magnetic field at this point is _______.JEE Mains 2024 Hard
- In the figure, given that \(V_{BB}\) supply can vary from \(0\) to \(5.0 \,V,\,\,V_{CC} = 5\,V,\) \(\beta _{dc} = 200,\,\,R_B = 100,\,k\Omega ,\) \(R_C = 1\,k\Omega \) an \(V_{BE} = 1.0\,V,\) The minimum base current and the input voltage at which the transistor will go to saturation, will be respectively
JEE Mains 2019 Hard - Find the magnetic field at the point \(P\) in figure. The curved portion is a semicircle connected to two long straight wires.
JEE Mains 2023 Medium - Four closed surfaces and corresponding charge distributions are shown below Let the respective electric fluxes through the surfaces be \({\phi _1},{\phi _2},{\phi _3}\) and \({\phi _4}\) . Then
JEE Mains 2017 Hard