Download App

STD 12 - 10. Wave optics — NEET STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceNEETSTD 12 - 10. Wave optics4 Marks
MCQ
In $Y.D.S.E$. using light of wavelength $\lambda$, intensity of light at a point on the screen with path differnce $\lambda$ is $M$ unit. Calculate intensity of light at a point where path difference is $\frac{\lambda }{3}$ is
  • A
    $\frac{M}{2}$
  • ✓
    $\frac{M}{4}$
  • C
    $\frac{M}{8}$
  • D
    $\frac{M}{16}$
✓

Answer

Correct option: B.
$\frac{M}{4}$
b
$I_{1}=I_{2}=I$

if $\Delta \mathrm{x}=1 \rightarrow$ constructive interference

 then $ \mathrm{I}_{\mathrm{R}} =\mathrm{I}_{\max }=4 \mathrm{I}=\mathrm{M} $

$\mathrm{I}_{1}= \mathrm{I}_{2}=\frac{\mathrm{M}}{4} $

Now, $\Delta x=\frac{\lambda}{3} \Rightarrow \Delta \phi=\frac{2 \pi}{3}$

$\mathrm{I}_{\mathrm{R}}=\mathrm{I}_{1}+\mathrm{I}_{2}+2 \sqrt{\mathrm{I}_{1}} \cdot \sqrt{\mathrm{I}_{2}} \cos \Delta \phi$

$=\frac{M}{4}+\frac{M}{4}+2 \sqrt{\frac{M}{4}} \sqrt{\frac{M}{4}} \cos \frac{2 \pi}{3}$

$\left(\because \cos \frac{2 \pi}{3}=-\frac{1}{2}\right)$

$I_{R}=\frac{M}{4}$

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

A spring-mass system vibrates such that mass travel on surface of coefficient of friction  $\mu$. Mass is released after compressing the spring by distance a and it travels upto  distance $b$ after its equilibrium position, then travelling from $x = -a$ to $x = b$ the reduction in its amplitude will be :-
→
The work done to take an electron from rest where potential is $-60\, V$ to another point where potential is $-20\, V$ is given by.....$eV$
→
The equation of state of some gases can be expressed as $\left( {P + \frac{a}{{{V^2}}}} \right)\,(V - b) = RT$. Here $P$ is the pressure, $V$ is the volume, $T$ is the absolute temperature and $a,\,b,\,R$ are constants. The dimensions of $'a'$ are
→
The upper half of an inclined plane with inclination $\phi$ is perfectly smooth, while the  lower half is rough. $A$ body starting from rest at the top will again come to rest at the  bottom, if the coefficient of friction for the lower half is given by-
→
A ball rolls off the top of a stairway with horizontal velocity $\mathrm{u}$. The steps are $0.1 \mathrm{~m}$ high and $0.1 \mathrm{~m}$ wide. The minimum velocity $\mathrm{u}$ with which that ball just hits the step $5$ of the stairway will be $\sqrt{\mathrm{x}} \mathrm{ms}^{-1}$ where $\mathrm{x}=$___________ [use $\mathrm{g}=10 \mathrm{~m} / \mathrm{s}^2$ ].
→
Quantam nature of light is explained by which of the following phenomenon
→
An astronaut orbiting the earth in a circular orbit $120\, km$ above the surface of earth, gently drops a spoon out of space-ship. The spoon will
→
${v_1}$ and ${v_2}$ are the velocities of sound at the same temperature in two monoatomic gases of densities ${\rho _1}$ and ${\rho _2}$ respectively. If $\frac{\rho _1}{\rho _2} = \frac{1}{4}$ then the ratio of velocities ${v_1}$ and ${v_2}$ will be
→
Two identical bar magnets with a length $10 \,cm $ and weight $50 \,gm$-weight are arranged freely with their like poles facing in a inverted vertical glass tube. The upper magnet hangs in the air above the lower one so that the distance between the nearest pole of the magnet is $3\,mm.$ Pole strength of the poles of each magnet will be.......$ amp × m$
→
An effective power of a combination of $5$ identical convex lenses which are kept in contact along the principal axis is $25 \mathrm{D}$. Focal length of each of the convex lens is:
→