Geometrical Optics | Physics JEE previous year questions with Solutions

Q 1 :

A scientist is observing a bacteria through a compound microscope. For better analysis and to improve its resolving power he should (Select the best option) [2023]

increase the wave length of the light
increase the refractive index of the medium between the object and objective lens
decrease the focal length of the eye piece
decrease the diameter of the objective lens

1

2

3

4

(2)

$P = \frac{2 μ \sin θ}{1.22 λ}$

Q 2 :

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 cm to focus the object again. The height of the liquid in the bucket is [2023]

75 cm
50 cm
18 cm
12 cm

1

2

3

4

(1)

$Shift = (d - \frac{d}{μ}) = 30 cm$

$d [1 - \frac{1}{\frac{5}{3}}] = 30$

$\Rightarrow d = \frac{30 \times 5}{2} = 75 cm$

Q 3 :

In a reflecting telescope, a secondary mirror is used to: [2023]

move the eyepiece outside the telescopic tube
make chromatic aberration zero
remove spherical aberration
reduce the problem of mechanical support

1

2

3

4

(1)

It has advantage of a large focal length in a short telescope.

Q 4 :

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 mm and apparent thickness of the glass slab at 5.00 mm. Travelling microscope has 20 divisions in one 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 _______. [2023]

0%

(41)

$u = \frac{h}{h'} = \frac{5.25}{5.00}$

$Least count = \frac{1}{20} cm - \frac{49}{50} \cdot \frac{1}{20} cm$

$= \frac{1}{50} \times \frac{1}{20} cm = 0.01 mm$

$\ln u = \ln h - \ln h'$

$\frac{d u}{u} = \frac{d h}{h} - \frac{d h'}{h'}$

$d u = [\frac{0.01}{5.25} + \frac{0.01}{5.00}] \frac{5.25}{5.00} = \frac{41}{10} \times 10^{- 3}$

Q 5 :

In a microscope the objective is having focal length $f_{o} = 2 cm$ and eye-piece is having focal length $f_{e} = 4 cm$ . The tube length is 32 cm. The magnification produced by this microscope for normal adjustment is __________. [2026]

0%

(100)

$m = \frac{l D}{f_{0} f_{e}}$

$= \frac{32}{2} \times \frac{25}{4}$

$m = 100$

Q 6 :

In a microscope of tube length 10 cm, two convex lenses are arranged with focal lengths of 2 cm and 5 cm. Total magnification obtained with this system for normal adjustment is ${(5)}^{k}$ . The value of $k$ is ______. [2026]

3.5
4
5
2

1

2

3

4

(4)

Topic Question Set

Q 1 :

A scientist is observing a bacteria through a compound microscope. For better analysis and to improve its resolving power he should (Select the best option) [2023]

Q 2 :

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 cm to focus the object again. The height of the liquid in the bucket is [2023]

Q 3 :

In a reflecting telescope, a secondary mirror is used to: [2023]

0%

Q 5 :

In a microscope the objective is having focal length $f_{o} = 2 cm$ and eye-piece is having focal length $f_{e} = 4 cm$ . The tube length is 32 cm. The magnification produced by this microscope for normal adjustment is __________. [2026]

0%

Q 6 :

In a microscope of tube length 10 cm, two convex lenses are arranged with focal lengths of 2 cm and 5 cm. Total magnification obtained with this system for normal adjustment is ${(5)}^{k}$ . The value of $k$ is ______. [2026]

Want Us to Email you About Special Offers & Updates?