Download App

STD 12 - 11. Dual nature of radiation and matter — JEE STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceJEESTD 12 - 11. Dual nature of radiation and matter4 Marks
MCQ
A certain metallic surface is illuminated with monochromatic light of wavelength, $\lambda$. The stopping potential for photo-electric current for this light is $3 V_0$  . If the same surface is illuminated with light of wavelength $2\lambda$, the stopping potential is $V_0$. The threshold wavelength for this surface for photo- electric effect is
  • A
    $6\lambda$
  • ✓
    $4\lambda$
  • C
    $\frac{\lambda }{4}$
  • D
    $\frac{\lambda }{6}$
✓

Answer

Correct option: B.
$4\lambda$
b
Case $(i)$, $e 3 V_{0}=\frac{h c}{\lambda}-\phi_{0}$     ......... $(i)$

Case $(ii)$, $e V_{0}=\frac{h c}{2 \lambda}-\phi_{0}$     .........$(ii)$

From $(i)$ and $(ii)$ we get,

$\frac{3 h c}{2 \lambda}-3 \phi_{0}=\frac{h c}{\lambda}-\phi_{0}$

or $\frac{3 h \lambda}{2 \lambda}-\frac{h c}{\lambda}=3 \phi_{0}-\phi_{0}$

or $\frac{h c}{2 \lambda}=2 \phi_{0}$ or $\phi_{0}=\frac{h c}{4 \lambda}$

$\therefore $ Threshold wavelength

$\lambda_{0}=\frac{h c}{\phi_{0}}=\frac{h c}{h c} \times 4 \lambda=4 \lambda$

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

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

Similar questions

One quality of a thermometer is that its heat capacity should be small. If $P$ is a mercury thermometer, $Q$ is a resistance thermometer and $R$ thermocouple type then
→
The maximum energy in thermal radiation from a source occurs at the wavelength $4000Å$ . The effective temperature of the source is ....... $K$
→
From the $v$ - $t$ graph shown. the ratio of distance to displacement in $25\,s$ of motion
→
The wing span of an aeroplane is $20$ $metre$. It is flying in a field, where the vertical component of magnetic field of earth is $5 ×10^{-5}$ tesla, with velocity $360\,km/h$. The potential difference produced between the blades will be.......$V$
→
The temperature of $100 \,gm$ of water is to be raised from $24^{\circ} C$ to $90^{\circ} C$ by adding steam to it. The mass of the steam required for this purpose is ........... $g$
→
A particle of mass $m = 1.67 \times 10^{-27}\, kg$ and charge $q = 1.6 \times 10^{-19} \, C$ enters a region of uniform magnetic field of strength $1$ $tesla$ along the direction shown in the figure. The speed of the particle is $10^7\, m/s.$ The magnetic field is directed along the inward normal to the plane of the paper. The particle enters the field at $C$ and leaves at $D.$ Then the angle $\theta$ must be :-.........$^o$
→
A system is oscillating with undamped simple harmonic motion. Then the
→
The voltage of $AC$ source varies with time according to the equation, $V = 100\, \sin 100\, \pi \, t \, \cos \,100\, \pi \,t$. Where $t$ is in second and $V$ is in volt. Then:-
→
A combination of two thin lenses of the same material with focal lengths ${f_1}$ and ${f_2}$, arranged on a common axis minimizes chromatic aberration, if the distance between them is
→
Which series of hydrogen atom lie in infrared region?
→