Question
Two coherent sources separated by distance d are radiating in phase having wavelength $\lambda$. A detector moves in a big circle around the two sources in the plane of the two sources. The angular position of $n = 4$ interference maxima is given as

Answer

(b) Here path difference at a point $P$ on the circle is given by
$\Delta x = d\cos \theta $ ….. (i)
For maxima at $P$
$\Delta x = n\lambda $ ….. (ii)
From equation (i) and (ii)
$n\lambda = d\cos \theta \Rightarrow \theta {\cos ^{ - 1}}\left( {\frac{{n\lambda }}{d}} \right) = {\cos ^{ - 1}}\left( {\frac{{4\lambda }}{d}} \right)$

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

Similar questions

A progressive wave travelling along the positive $x-$ direction is represented by $y(x, t) = A\,sin\,\left( {kx - \omega t + \phi } \right)$. Its snapshot at $t = 0$ is given in the figure For this wave, the phase $\phi $ is
A person uses a lens of power $+ 3D $ to normalise vision. Near point of hypermetropic eye is.......$m$
In the figure shown the velocity of different blocks is shown. The velocity of $C$ is $.........\,m/s$
A body has speed $V, 2V$ and $3V$ in first $1/3$ of distance $S$, seconds $1/3$ of $S$ and third $1/3$ of $S$ respectively. Its average speed will be
A light rod of length $l$ has two masses $m_1$ and $m_2$ attached to its two ends. The moment of inertia of the system about an axis perpendicular to the rod and passing through the centre of mass is 
If capillary experiment is performed in vacuum then for a liquid there
At high altitude, a body explodes at rest into two equal fragments with one fragment receiving horizontal velocity of $10 \,m/s$. Time taken by the two radius vectors connecting point of explosion to fragments to make $90^o $ is ............ $\mathrm{s}$
A bob of mass $'m'$ suspended by a thread of length $l$ undergoes simple harmonic oscillations with time period ${T}$. If the bob is immersed in a liquid that has density $\frac{1}{4}$ times that of the bob and the length of the thread is increased by $1 / 3^{\text {rd }}$ of the original length, then the time period of the simple harmonic oscillations will be :-
A mass is hanging on a spring balance which is kept in a lift. The lift ascends. The spring balance will show in its reading
$10$ resistors each of resistance $10\,\Omega$ can be connected in such as to get maximum and minimum equivalent resistance. The ratio of maximum and minimum equivalent resistance will be $..........$.