Download App

10. Wave optics — Physics STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 SciencePhysics10. Wave optics1 Mark
MCQ
In Young's double slit experiment, light from two identical sources are superimposing on a screen. The path difference between the two lights reaching at a point on the screen is $\frac{7 \lambda}{4}$. The ratio of intensity of fringe at this point with respect to the maximum intensity of the fringe is :
  • ✓
    $1 / 2$
  • B
     $3 / 4$
  • C
     $1 / 3$
  • D
     $1 / 4$
✓

Answer

Correct option: A.
$1 / 2$
a
$ \Delta \mathrm{x}=\frac{7 \lambda}{4} $

$ \phi=\frac{2 \pi}{\lambda} \Delta \mathrm{x}=\frac{2 \pi}{\lambda} \times \frac{7 \lambda}{4}=\frac{7 \pi}{2} $

$ \mathrm{I}=\mathrm{I}_{\max } \cos ^2\left(\frac{\phi}{2}\right) $

$ \frac{\mathrm{I}}{\mathrm{I}_{\max }}=\cos ^2\left(\frac{\phi}{2}\right)=\cos ^2\left(\frac{7 \pi}{2 \times 2}\right)=\cos ^2\left(\frac{7 \pi}{4}\right) $

$=\cos ^2\left(2 \pi-\frac{\pi}{4}\right) $

$=\cos ^2 \frac{\pi}{4} $

$=\frac{1}{2}$

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

More "M.C.Q (1 Marks)" from 10. Wave optics→10. Wave optics — all question types→Physics STD 12 Science question papers→CBSE Board STD 12 Science question papers→CBSE Board question paper generator→

Similar questions

Find equivalent capacitance between $A$ and $B$
→
The ionisation energy of hydrogen atom is $13.6\; eV$, the ionisation energy of a singly ionised helium atom would be  ....... $eV$
→
The magnetic field $B$ crossing normally a square metallic plate of area $4\,m ^2$ is changing with time as shown in figure. The magnitude of induced $emf$ in the plate during $t=2\,s$ to $t=4\,s$, is $..........\,mV$
→
A coil of $200$ turns and area $0.20 \mathrm{~m}^2$ is rotated at half a revolution per second and is placed in uniform magnetic field of $0.01 \mathrm{~T}$ perpendicular to axis of rotation of the coil. The maximum voltage generated in the coil is $\frac{2 \pi}{\beta}$ volt. The value of $\beta$ is______________
→
$12$ cells each having the same emf are connected in series and are kept in a closed box. Some of the cells are wrongly connected. This battery is connected in series with an ammeter and two cells identical with each other and also identical with the previous cells. The current is $3\, A$ when the external cells aid this battery and is $2\,A$ when the cells oppose the battery. How many cells in the battery are wrongly connected :-
→
Two equal charges q are placed at a distance of 2a and a third charge -2q is placed at the midpoint. The potential energy of the system is
→
A uniform magnetic field $B$ that is perpendicular to the plane of the page now passes through the loops, as shown. The field is confined to a region of radius $a$ , where $a < b$ , and is changing at a constant rate. The induced emf in the wire loop of radius $b$ is $\varepsilon $. What is the induced emf in the wire loop of radius $2b$ 
→
A thin rectangular magnet suspended freely has a period of oscillation equal to $T$. Now it is broken into two equal halves (each having half of the original length) and one piece is made to oscillate freely in the same field. If its period of oscillation is $T'$, then ratio $\frac{{T'}}{T}$is
→
Which of the following are not electromagnetic waves
→
A $100\, mH$ coil carries a current of $1\, ampere$. Energy stored in its magnetic field is......$J$
→