A person is suffering from myopic defect. He is able to see clear… - Vidyadip

MCQ

A person is suffering from myopic defect. He is able to see clear objects placed at $15 \mathrm{~cm}$. What type and of what focal length of lens he should use to see clearly the object placed $60 \mathrm{~cm}$ away

✓
Concave lens of $20 \mathrm{~cm}$ focal length
B
Convex lens of $20 \mathrm{~cm}$ focal length
C
Concave lens of $12 \mathrm{~cm}$ focal length
D
Convex lens of $12 \mathrm{~cm}$ focal length

✓

Answer

Correct option: A.

Concave lens of $20 \mathrm{~cm}$ focal length

For viewing far objects, concave lenses are used and for concave lens$u=$ wants to see $=-60 \mathrm{~cm} ; v=$ can see $=-15 \mathrm{~cm}$
so from $\frac{1}{f}=\frac{1}{v}-\frac{1}{u} $
$\Rightarrow f=-20 \mathrm{~cm}$.

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 "MCQ" from Ray Optics→Ray Optics — all question types→JEE physics STD 12 Science question papers→CBSE Board STD 12 Science question papers→CBSE Board question paper generator→

Similar questions

If a shell fired from a cannon, explodes in mid air, then

An iron ball and a wooden ball of the same radius are released from a height ' $h$ ' in vacuum. The time taken by both of them to reach the ground is

Relative difference of focal lengths of objective and eye lens in the microscope and telescope is given as

In which of the following systems will the radius of the first orbit $(n=1)$ be minimum

The dimensions of magnetic flux are

A body of mass $5 \mathrm{~kg}$ moving with a velocity $10 \mathrm{~m} / \mathrm{s}$ collides with another body of the mass $20 \mathrm{~kg}$ at, rest and comes to rest. The velocity of the second body due to collision is

Consider the three waves $z_1, z_2$ and $z_3$ as $z_1=A \sin (k x-\omega t), z_2=A \sin (k x+\omega t)$ and $z_3=A \sin (k y-\omega t)$. Which of the following represents a standing wave

Work done by magnetic field of $1\,tesla$ on a particle of chargs $1\,C$ moving with speed $5\,m/s$ in one second........$J$

In short wave communication waves of which of the following frequencies will be reflected back by the ionospheric layer, having electron density $10$ per $m$

The walls of the halls built for music concerts should