Embibe Experts Solutions for Chapter: Ray Optics, Exercise 1: JEE Main - 20 July 2021 Shift 1

An object is placed on the principal axis of convex lens of focal length $10 \mathrm{cm}$ as shown. A plane mirror is placed on the other side of lens at a distance of $20 \mathrm{cm}$. The image produced by the plane mirror is $5 \mathrm{cm}$ inside the mirror. The distance of the object from the lens is ____ $\mathrm{cm}$.

In an experiment of measuring the refractive index of a glass slab using travelling microscope in physics lab, a student measures real thickness of the glass slab as $5.25 \mathrm{mm}$ and apparent thickness of the glass slab at $5.00 \mathrm{mm}$. Travelling microscope has $20$ divisions in one $\mathrm{cm}$ on main scale and $50$ divisions on Vernier scale is equal to $49$ divisions on main scale. The estimated uncertainty in the measurement of refractive index of the slab is $\frac{x}{10}\times {10}^{-3}$, where $x$ 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:

A thin prism $P_1$ with an angle $6°$ 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 :

In a medium the speed of light wave decreases to $0.2$ times to its speed in free space. The ratio of relative permittivity to the refractive index of the medium is $x:1$. The value of $x$ is ______.

(Given speed of light in free space $=3\times {10}^8 \mathrm{m} {\mathrm{s}}^{-1}$ and for the given medium ${\mu }_r=1$)

A microscope is focused on an object at the bottom of a bucket. If liquid with refractive index $\frac{5}{3}$ is poured inside the bucket, then microscope have to be raised by $30\mathrm{cm}$ to focus the object again. The height of the liquid in the bucket is :

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 ______.

Two objects $A and B$ 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: