JEE Main Physics — Optics previous year questions with solutions.
As shown in the figure, a plane mirror is fixed at a height of $50\mathrm{cm}$ from the bottom of tank containing water $(\mu =\frac{4}{3})$. The height of water in the tank is $8\mathrm{cm}$. A small bulb is placed at the bottom of the water tank. The distance of image of the bulb formed by mirror from the bottom of the tank is ______ $\mathrm{cm}$. 
A thin cylindrical rod of length $10\mathrm{cm}$ is placed horizontally on the principle axis of a concave mirror of focal length $20\mathrm{cm}$. The rod is placed in a such a way that mid point of the rod is at $40\mathrm{cm}$ from the pole of mirror. The length of the image formed by the mirror will be $\frac{x}{3}\mathrm{cm}$. The value of $x$ is ______.
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Assertion A: The phase difference of two light waves change if they travel through different media having same thickness, but different indices of refraction. Reason R: The wavelengths of waves are different in different media. In the light of the above statements, choose the most appropriate answer from the options given below
Given below are two statements : Statement I : If the Brewster's angle for the light propagating from air to glass is ${\theta }_{B}$, then Brewster's angle for the light propagating from glass to air is $\frac{\pi }{2}-{\theta }_{B}$. Statement II : The Brewster's angle for the light propagating from glass to air is ${\mathrm{tan}}^{-1}({\mu }_{g})$, where ${\mu }_{g}$ is the refractive index of glass. In the light of the above statements, choose the correct answer from the options given below :
‘$n$’ polarizing sheets are arranged such that each makes an angle $45^{\circ}$ with the proceeding sheet. An unpolarized light of intensity $I$ is incident into this arrangement. The output intensity is found to be $\frac{I}{64}$ . The value of $n$ will be:
A $2$ meter long scale with least count of $0.2\mathrm{cm}$ is used to measure the locations of objects on an optical bench. While measuring the focal length of a convex lens, the object pin and the convex lens are placed at $80\mathrm{cm}$ mark and $1m$ mark, respectively. The image of the object pin on the other side of lens coincides with image pin that is kept at $180\mathrm{cm}$ mark. The $%$ error in the estimation of focal length is:
A single slit of width $a$ is illuminated by a monochromatic light of wavelength $600\mathrm{nm}$. The value of $a$ for which first minimum appears at $\theta ={30}^{o}$ on the screen will be :
The critical angle for a denser-rarer interface is $45^{\circ}$. The speed of light in rarer medium is $3\times {10}^{8}m{s}^{-1}$. The speed of light in the denser medium is:
Unpolarised light of intensity $32W{m}^{-2}$ passes through the combination of three polaroids such that the pass axis of the last polaroids is perpendicular to that of the pass axis of first polaroids. If intensity of emerging light is $3W{m}^{-2}$, then the angle between pass axis of first two polaroids is _________$^{\circ}$.
Two polaroids $A\text{and}B$ are placed in such a way that the pass-axis of polaroids are perpendicular to each other. Now, another polaroid $C$ is placed between $A\text{and}B$ bisecting angle between them. If intensity of unpolarised light is ${I}_{0}$ then intensity of transmitted light after passing through polaroid $B$ will be :
A monochromatic light wave with wavelength ${\lambda }_{1}$ and frequency ${\nu }_{1}$ in air enters another medium. If the angle of incidence and angle of refraction at the interface are $45^{\circ}$ and $30^{\circ}$ respectively, then the wavelength ${\lambda }_{2}$ and frequency ${\nu }_{2}$ of the refracted wave are:
A convex lens of refractive index $1.5$ and focal length $18\mathrm{cm}$ in air is immersed in water. The change in focal length of the lens will be_____$\mathrm{cm}$. (Given refractive index of water$=\frac{4}{3}$)
A thin prism ${P}_{1}$ with an angle $6^{\circ}$ and made of glass of refractive index $1.54$ is combined with another prism ${P}_{2}$ made from glass of refractive index $1.72$ to produce dispersion without average deviation. The angle of prism ${P}_{2}$ is :
A person has been using spectacles of power $-1.0$ diopter for distant vision and a separate reading glass of power $2.0$ diopters. What is the least distance of distinct vision for this person:
The radius of curvature of each surface of a convex lens having refractive index $1.8$ is $20\mathrm{cm}$. The lens is now immersed in a liquid of refractive index $1.5$. The ratio of power of lens in air to its power in the liquid will be $x:1$. The value of $x$ is
As shown in the figure, a combination of a thin plano-concave lens and a thin plano-convex lens is used to image an object placed at infinity. The radius of curvature of both the lenses is $30\mathrm{cm}$ and refraction index of the material for both the lenses is $1.75$. Both the lenses are placed at distance of $40\mathrm{cm}$ from each other. Due to the combination, the image of the object is formed at distance $x=$ ______ $\mathrm{cm}$, from concave lens. 
As shown in figures, three identical polaroids ${P}_{1}$, ${P}_{2}$ and ${P}_{3}$ are placed one after another. The pass axis of ${P}_{2}$ and ${P}_{3}$ are inclined at angle of $60º$ and $90º$ with respect to axis of ${P}_{1}$. The source $S$ has an intensity of $256W{m}^{-2}$. The intensity of light at point $O$ is _____$W{m}^{-2}$. 
In a reflecting telescope, a secondary mirror is used to:
Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R Assertion A : The beam of electrons shows wave nature and exhibit interference and diffraction. Reason R : Davisson Germer Experimentally verified the wave nature of electrons. In the light of the above statements. Choose the most appropriate answer from the options given below :
In Young’s double slit experiment, two slits ${S}_{1}$ and ${S}_{2}$ are $d$ distance apart and the separation from slits to screen is $D$ (as shown in figure). Now if two transparent slabs of equal thickness $0.1\mathrm{mm}$ but refractive index $1.51$ and $1.55$ are introduced in the path of beam $(\lambda =4000Å)$ from ${S}_{1}$ and ${S}_{2}$ respectively. The central bright fringe spot will shift by ________ number of fringes. 
As shown in the figure, in Young's double slit experiment, a thin plate of thickness $t=10\mu m$ and refractive index $\mu =1.2$ is inserted infront of slit ${S}_{1}$. The experiment is conducted in air ($\mu =1$) and uses a monochromatic light of wavelength $\lambda =500\mathrm{nm}$. Due to the insertion of the plate, central maxima is shifted by a distance of $x{\beta }_{0}$. ${\beta }_{0}$ is the fringe-width before the insertion of the plate. The value of the $x$ is ______. 
In a Young’s double slit experiment, two slits are illuminated with a light of wavelength $800\mathrm{nm}$. The line joining ${A}_{1}P$ is perpendicular to ${A}_{1}{A}_{2}$ as shown in the figure. If the first minimum is detected at $P$, the value of slits separation $a$ will be :  The distance of screen from slits $D=5\mathrm{cm}$.
Two objects $AandB$ are placed at $15\mathrm{cm}\mathrm{and}25\mathrm{cm}$ from the pole in front of a concave mirror having radius of curvature $40\mathrm{cm}$. The distance between images formed by the mirror is:
Two convex lenses of focal length $20\mathrm{cm}$ each are placed coaxially with a separation of $60\mathrm{cm}$ between them. The image of the distant object formed by the combination is at _____ $\mathrm{cm}$ from the first lens.