WBJEE · Physics · Wave Optics
Light of wavelength \(6000 Ã…\) is incident on a thin glass plate of \(\mu = 1.5\) such that the angle of refraction into the plate is \(60^{\circ}\). Calculate the smallest thickness of the plate which will make dark fringe by reflected beam interference.
- A \(1.5 \times 10^{-7} \mathrm{~m}\)
- B \(2 \times 10^{-7} \mathrm{~m}\)
- C \(3.5 \times 10^{-7} \mathrm{~m}\)
- D \(4 \times 10^{-7} \mathrm{~m}\)
Answer & Solution
Correct Answer
(D) \(4 \times 10^{-7} \mathrm{~m}\)
Step-by-step Solution
Detailed explanation
For reflected light, condition of destructive interference, \(2 \mu t \cos r-\frac{\lambda}{2}=(2 n+1) \frac{\lambda}{2}\) \(\Rightarrow 2 \mu \mathrm{t} \cos \mathrm{r}=(2 \mathrm{n}+1) \frac{\lambda}{2}+\frac{\lambda}{2}\) For minimum thickness of the plate, \(\mathrm{n}=0\),…
See the Complete Solution
Get step-by-step explanations for this and 2.5 Lakh+ more JEE, NEET & CET questions.
- Unlock all solutions
- Practice the full chapter
- Track accuracy across PYQs
4.8 rated on Google Play · 14,000+ reviews
More questions from Physics
-
A parallel beam of light is incident on a glass prism in the shape of a quarter cylinder of radius \(R=0.05 \mathrm{m}\) and refractive index \(n=1.5,\) placed on a horizontal table as shown in the figure. Beyond the cylinder, a patch of light is found whose the nearest distance \(x\) from the cylinder isWBJEE 2017 Medium - A plano-convex lens \((f=20 \mathrm{~cm})\) is silvered at plane surface. Now focal length will be :WBJEE 2010 Easy
- A horizontal semi-circular wire of radius \(\mathrm{r}\) is connected to a battery through two similar springs \(\mathrm{X}\) and \(\mathrm{Y}\) to an electric cell, which sends current I through it. A vertically downward uniform magnetic field B is applied on the wire, as shown in the figure. What is the force acting on each spring?
WBJEE 2022 Medium - The frequency of the first overtone of a closed pipe of length \(l_{1}\) is equal to that of the first. overtone of an open pipe of length \(l_{2}\). The ratio of their lengths \(\left(l_{1}: l_{2}\right)\) isWBJEE 2012 Easy
-
For two types of magnetic materials \(A\) and \(B\), variation of \(\frac{1}{\chi}\) ( \(\chi:\) susceptibility) vs. temperature \(T\) is shown in the figure. ThenWBJEE 2021 Easy - The force \(\mathrm{F}\) acting on a particle moving in a straight line is shown below. What is the work done by the force on the particle in the \(1^{\text {st }}\) meter of the trajectory?
WBJEE 2009 Easy
More PYQs from WBJEE
- Among the following carbocations :
(I) \(\mathrm{Ph}_{2}\stackrel{+}{\mathrm{C}} \mathrm{CH}_{2} \mathrm{Me}(\mathrm{II}) \mathrm{Ph} \mathrm{CH}_{2} \mathrm{CH}_{2} \stackrel{+}{\mathrm{C}} \mathrm{HPh}\)
(III) \(\mathrm{Ph}_{2} \mathrm{CH} \stackrel{+}{\mathrm{C}} \mathrm{HMe}\) (IV) \(\mathrm{Ph}_{2} \mathrm{C}(\mathrm{Me}) \stackrel{+}{\mathrm{C}} H_{2}\) the order of stability is :WBJEE 2012 Easy - A straight conductor \(0.1 \mathrm{m}\) long moves in uniform magnetic field \(0.1 \mathrm{T}\). The velocity the conductor is \(15 \mathrm{m} / \mathrm{s}\) and is directer perpendicular to the field. The emf inducod between the two ends of the conductor isWBJEE 2015 Easy
- Let \(I=\int_{0}^{{100 \pi }} \sqrt{(1-\cos 2 x)} d x\), thenWBJEE 2017 Medium
- The value of the integral \(\int_0^{\pi / 2} \sin ^5 x d x\) isWBJEE 2010 Medium
- Let \(L\) be the length and d be the diameter of cross-section of a wire. Wires of the same material with different \(L\) and \(d\) are subjected to the same tension along the length of the wire. In which of the following cases, the extension of wire will be the maximum?WBJEE 2012 Easy
- Two base balls (masses: \(m_1=100 \mathrm{~g}\), and \(m_2=50 \mathrm{~g}\) ) are thrown. Both of them move with uniform velocity, but the velocity of \(m_2\) is 1.5 times that of \(m_1\). The ratio of de Broglie wavelengths \(\lambda\left(m_1\right): \lambda\left(m_2\right)\) is given byWBJEE 2023 Easy