If \(2.5 \times 10^{-6\,} N\) average force is exerted by a light wave on a non-reflecting surface of \(30\, cm ^{2}\) area during \(40\) minutes of time span, the energy flux of light just before it falls on the surface is .................. \(W / cm ^{2}\) (Round off to the Nearest Integer) (Assume complete absorption and normal incidence conditions are there)

Pick an option to check your answer.

Verified Solution

Answer & Solution

Correct Answer

(D) \(25\)

Step-by-step Solution

Detailed explanation

\(F=\frac{I A}{C}\)

\(I=\frac{F C}{A}=\frac{2.5 \times 10^{-6} \times 3 \times 10^{8}}{30}=25 W / cm ^{2}\)

Same subject

The relation between time ' \(t\) ' and distance ' \(x\) ' is \(t=\) \(\alpha x^2+\beta x\), where \(\alpha\) and \(\beta\) are constants. The relation between acceleration \((a)\) and velocity \((v)\) is _______.

JEE Mains 2024 Hard
A particle of mass \(m\) is moving with speed \(2\, v\) collides with a mass \(2\,m\) moving with speed \(v\) in the same direction. After collision, the first mass is stopped completely while the second one splits into two particles each of mass \(m\), which move at angle \(45^o\) with respect to the original direction. The speed of each of the moving particle will be

JEE Mains 2019 Medium
A light source of wavelength \(\lambda\) illuminates a metal surface and electrons are ejected with maximum kinetic energy of 2 eV . If the same surface is illuminated by a light source of wavelength \(\frac{\lambda}{2}\), then the maximum kinetic energy of ejected electrons will be (The work function of metal is 1 eV )

JEE Mains 2025 Easy
In a certain thermodynamical process, the pressure of a gas depends on its volume as \(kV ^{3}\). The work done when the temperature changes from \(100^{\circ} C\) to \(300^{\circ} C\) will be .......... \(nR\), where \(n\) denotes number of moles of a gas.

JEE Mains 2021 Hard
A submarine experiences a pressure of \(5.05\times 10^6\,Pa\) at a depth of \(d_1\) in a sea. When it goes further to a depth of \(d_2,\) it experiences a pressure of \(8.08\times 10^6\,Pa.\) Then \(d_2 -d_1\) is approximately ........ \(m\) (density of water \(= 10^3\,kg/m^3\) and acceleration due to gravity \(= 10\,ms^{-2}\) )

JEE Mains 2019 Medium
Consider a modified Bernoulli equation.
\(\left( P +\frac{ A }{ Bt ^2}\right)+\rho g ( h + Bt )+\frac{1}{2} \rho V^2=\) constant
If \(t\) has the dimension of time then the dimensions of A and B are _________ , _________ respectively.

JEE Mains 2026 Hard

Explore more questions on app

From JEE Mains

A system of three polarizers \(P_1, P_2, P_3\) is set up such that the pass axis of \(P_3\) is crossed with respect to that of \(P_1\). The pass axis of \(P_2\) is inclined at \(60^o\) to the pass axis of \(P_3\). When a beam of unpolarized light of intensity \(I_0\) is incident on \(P_1\), the intensity of light transmitted by the three polarizers is \(I\). The ratio \((I_0/I)\) equals (nearly)

JEE Mains 2019 Hard
A small uncharged conducting sphere is placed in contact with an identical sphere but having \(4 \times 10^{-8} \mathrm{C}\) charge and then removed to a distance such that the force of repulsion between them is \(9 \times 10^{-3} \mathrm{~N}\). The distance between them is (Take \(\frac{1}{4 \pi \epsilon_{\mathrm{o}}}\) as \(9 \times 10^9 \mathrm{in} \mathrm{SI}\) units)

JEE Mains 2025 Hard
Two blocks of mass \(2 \mathrm{~kg}\) and \(4 \mathrm{~kg}\) are connected by a metal wire going over a smooth pulley as shown in figure. The radius of wire is \(4.0 \times 10^{-5}\) \(\mathrm{m}\) and Young's modulus of the metal is \(2.0 \times 10^{11} \mathrm{~N} / \mathrm{m}^2\). The longitudinal strain developed in the wire is \(\frac{1}{\alpha \pi}\). The value of \(\alpha\) is _______. [Use \(\mathrm{g}=10 \mathrm{~m} / \mathrm{s}^2\) )

JEE Mains 2024 Hard
A force of \(- P \hat{k}\) acts on the origin of the coordinate system. The torque about the point \((2,-3)\) is \(P(a \hat{i}+b \hat{j})\), the ratio of \(\frac{a}{b}\) is \(\frac{x}{2}\). The value of \(x\) is

JEE Mains 2023 Medium
Two identical capacitors have same capacitance \(C\). One of them is charged to the potential \(\mathrm{V}\) and other to the potential \(2 \mathrm{~V}\). The negative ends of both are connected together. When the positive ends are also joined together, the decrease in energy of the combined system is _______.

JEE Mains 2024 Hard

Explore more questions on app