When light of a given wavelength is incident on a metallic surfac… - Vidyadip

Question

When light of a given wavelength is incident on a metallic surface, the minimum potential needed to stop the emitted photoelectrons is $6.0 V$. This potential drops to $0.6 V$ if another source with wavelength four times that of the first one and intensity half of the first one is used. What are the wavelength of the first source and the work function of the metal, respectively? $\left[\right.$ Take $\left.=\frac{h c}{c}=1.24 \times 10^{-6} Jm ^{-1}.\right]$

✓

Answer

$\frac{ hc }{\lambda}=\phi+6 \quad \ldots \text { (i) }$ $. . . (1)$

$\frac{ hc }{4 \lambda}=\phi+0.6 \quad \ldots \text { (ii) }$ $. . . (2)$

$\frac{3 hc }{4 \lambda}=5.4 eV \quad \therefore \phi=1.2 eV$

$\Rightarrow \frac{3}{4} \times \frac{6.63 \times 10^{-24} \times 3 \times 10^8}{5.4 \times 1.6 \times 10^{-19}}=\lambda=1.72 \times 10^{-7} m$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

NEET STD 11 Science question papers→Gujarat Board STD 11 Science question papers→Gujarat Board question paper generator→

Similar questions

If fundamental frequency of closed pipe is $50\,Hz$ then frequency of $2^{nd}$ overtone is .... $Hz$

Find equivalent capacitance between $A$ and $B$

In an $\alpha -$ decay the Kinetic energy of $\alpha$ particle is $48 \,MeV$ and $Q-$ value of the reaction is $50 \,MeV.$ The mass number of the mother nucleus is : (Assume that daughter nucleus is in ground state)

A body of mass $8\,kg$ is moved by a force $F = 3x\,N,$ where $x$ is the distance covered. Initial position is $x = 2\,m$ and the final position is $x = 10\,m$. The initial speed is $0.0\,m/s.$ The final speed is ........... $m/s$

An assembly of identical spring-mass systems is placed on a smooth horizontal surface as shown. At this instant, the springs are relaxed. The left mass is displaced to the/left and theiright mass is displaced to the right by same distance and released. The resulting collision is elastic. The time period of the oscillations of system is

A small soap bubble of radius $4\,cm$ is trapped inside another bubble of radius $6\,cm$ without any contact. Let $P_2$ be the pressure inside the inner bubble and $P_0$ the pressure outside the outer bubble. Radius of another bubble with pressure difference $P_2 - P_0$ between its inside and outside would be....... $cm$

Ten capacitor are joined in parallel and charged with a battery up to a potential $V$. They are then disconnected from battery and joined again in series then the potential of this combination will be.......$V$

Particles used in the Rutherford's scattering experiment to deduce the structure of atoms

When a forward bias is applied to a $p-n$ junction, it

A particle of mass $m$ projected with a velocity ' $u$ ' making an angle of $30^{\circ}$ with the horizontal. The magnitude of angular momentum of the projectile about the point of projection when the particle is at its maximum height $\mathrm{h}$ is :