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Physics M.C.Q (1 Marks)

Ray Optics and Optical Instruments · Gujarat Board (GSEB) STD 12 Science (GSEB - English Medium). 39 questions.

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M.C.Q (1 Marks)

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39 questions · auto-graded multiple-choice test.

MCQ 11 Mark
If the magnification of objective and eyepiece in a compound microscope is ' $m_o$ ' and ' $m_e$ ' respectively, then the total magnifying power $( m )$ of the microscope will be :
  • A
    $m_o+m_e$
  • B
    $m_e-m_o$
  • ✓
    $m_o \cdot m_e$
  • D
    $\frac{m_o}{m_e}$
Answer
Correct option: C.
$m_o \cdot m_e$
(C) - $m_o \cdot m_e$
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MCQ 21 Mark
If the magnification of optical instrument is negative, then the image will always be formed :
  • ✓
    Real and inverted
  • B
    Virtual and erect
  • C
    Real and erect
  • D
    Virtual and inverted
Answer
Correct option: A.
Real and inverted
(A) - Real and inverted
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MCQ 31 Mark
What will be the focal length of a convex lens whose power is +2.5 D ?
  • A
    50 cm
  • B
    25 cm
  • C
    250 cm
  • ✓
    40 cm
Answer
Correct option: D.
40 cm
(D) - 40 cm
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MCQ 41 Mark
If the refractive index of denser medium 1 relative to rare medium 2 is $n_{12}$ and the critical angle for the pair of these mediums is $i_{ c }$, then the relationship between $n _{12}$ and $i_c$ is :
  • A
    $n_{12}=\sin i_c$
  • B
    $n_{12}=\tan i_c$
  • C
    $n_{12}=\frac{1}{\tan i_c}$
  • ✓
    $n_{12}=\frac{1}{\sin i_c}$
Answer
Correct option: D.
$n_{12}=\frac{1}{\sin i_c}$
(D) - $n_{12}=\frac{1}{\sin i_c}$
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MCQ 51 Mark
Which of objective lens is used in reflector telescope :
  • A
    plane mirror
  • ✓
    concave mirror
  • C
    convex lens
  • D
    prism
Answer
Correct option: B.
concave mirror
(B) - concave mirror
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MCQ 61 Mark
In a microscope, the focal length of the objective lens in comparison to focal length of the eye lens is :
  • ✓
    less
  • B
    more
  • C
    equal
  • D
    nothing can be said
Answer
Correct option: A.
less
(A) - lees
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MCQ 71 Mark
The focal lengths of the objective lens and the eye lens of a telescope are $f_o$ and $f_e$ respectively. Its magnifying power is approximately :
  • ✓
    $\frac{f_o}{f_e}$
  • B
    $f_o-f_e$
  • C
    $f_{ o } f_{ e }$
  • D
    $f_e+\frac{f_o}{2}$
Answer
Correct option: A.
$\frac{f_o}{f_e}$
(A) - $\frac{f_o}{f_e}$
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MCQ 81 Mark
A ray of light transmits from glass (refractive index $=$ $3 / 2$ ) to water (refractive index $=4 / 3$ ). The value of critical angle will be :
  • A
    $\sin ^{-1}\left(\frac{1}{2}\right)$
  • B
    $\sin ^{-1}\left(\sqrt{\frac{8}{9}}\right)$
  • ✓
    $\sin ^{-1}\left(\frac{8}{9}\right)$
  • D
    $\sin ^{-1}\left(\frac{5}{7}\right)$
Answer
Correct option: C.
$\sin ^{-1}\left(\frac{8}{9}\right)$
(C) - $\sin ^{-1}\left(\frac{8}{9}\right)$
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MCQ 91 Mark
When the length of the tube of a microscope is increased, the magnifying power will be :
  • ✓
    decreases
  • B
    increases
  • C
    remains unchanged
  • D
    can be more or less
Answer
Correct option: A.
decreases
(A) - decreases
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MCQ 101 Mark
The focal lengths of the objective and eye lens of a microscope are 4 cm and 8 cm respectively, and the distance of the object from the eye lens is 4.5 cm ., then the magnifying power will be :
  • A
    18
  • ✓
    32
  • C
    64
  • D
    20
Answer
Correct option: B.
32
(B) - 32
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MCQ 111 Mark
A person suffering from myopia cannot see clearly :
  • A
    nearby objects
  • ✓
    distant objects
  • C
    neither near nor far objects
  • D
    horizontal and vertical lines
Answer
Correct option: B.
distant objects
(B) - distant objects
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MCQ 121 Mark
The power of a person's spectacle lenses is +2 D . He is suffering from which of the following defects?
  • ✓
    From hypermetropia
  • B
    From myopia
  • C
    From colour blindness
  • D
    From Presbyopia
Answer
Correct option: A.
From hypermetropia
(A) - From hypermetropia
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MCQ 131 Mark
The focal lengths of the objective and eye lens of a microscope are 4 cm and 8 cm respectively and the distance of the object from the objective is 4.5 cm , then the magnifying power will be :
  • A
    18
  • ✓
    32
  • C
    64
  • D
    20
Answer
Correct option: B.
32
(B) - 32
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MCQ 141 Mark
The magnifying power of a telescope is $M$. If the focal length of the eye lens is doubled, then the magnifying power will be :
  • A
    2 M
  • ✓
    $\frac{1}{2} M$
  • C
    $\sqrt{2} M$
  • D
    3 M
Answer
Correct option: B.
$\frac{1}{2} M$
(B) - $\frac{1}{2} M$
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MCQ 151 Mark
When a bi-convexo lens of glass with refractive index 1.47 is immersed in a liquid, then it behaves like a plane glass sheet, it means that the refractive index of the liquid is :
  • ✓
    equivalent to the refractive index of glass
  • B
    less than one
  • C
    more than the refractive index of glass
  • D
    less than the refractive index of glass
Answer
Correct option: A.
equivalent to the refractive index of glass
(A) - equivalent to the refractive index of glass
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MCQ 161 Mark
If the refractive index of a prism is $\sqrt{2}$ and the angle of refraction is $60^{\circ}$, then its minimum deviation angle will be :
  • A
    $15^{\circ}$
  • ✓
    $30^{\circ}$
  • C
    $45^{\circ}$
  • D
    $60^{\circ}$
Answer
Correct option: B.
$30^{\circ}$
(B) - $30^{\circ}$
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MCQ 171 Mark
The focal length of a convex lens is 2.5 cm. The value of its maximum magnifying power will be :
  • A
    25
  • B
    52
  • ✓
    11
  • D
    1.1
Answer
Correct option: C.
11
(C) - 11
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MCQ 181 Mark
The radii of curvature of a convex lens are 15 cm and 30 cm respectively. Its refractive index is 1.5 . The focal length of the lens will be :
  • ✓
    20 cm
  • B
    -20 cm
  • C
    60 cm
  • D
    -60 cm
Answer
Correct option: A.
20 cm
(A) - 20 cm
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MCQ 191 Mark
$\lambda$ ray of light passes through a prism of refractive index $\sqrt{2}$ in such a way that its angle of incidence is twice of the angle of refraction and there is minimum deviation in the ray. The angle of the prism will be :
  • A
    $45^{\circ}$
  • ✓
    $90^{\circ}$
  • C
    $0^{\circ}$
  • D
    none of these
Answer
Correct option: B.
$90^{\circ}$
(B) - $90^{\circ}$
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MCQ 201 Mark
When half of a lens is wrapped in a black cloth, what will be the effect on the image formed by the lens?
  • A
    The image will disappear
  • B
    Will have no effect
  • C
    The image will become half its size
  • ✓
    The brightness of the image will decrease
Answer
Correct option: D.
The brightness of the image will decrease
(D) - The brightness of the image will decrease
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MCQ 211 Mark
The power of a convex lens is :
  • A
    Negative
  • ✓
    Positive
  • C
    Zero
  • D
    Imaginary
Answer
Correct option: B.
Positive
(B) - Positive
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MCQ 221 Mark
A compound lens has been manufactured by combining lenses of power +2.50 D and -3.75 D . The value of its focal length in cm will be :
  • A
    40
  • B
    -40
  • ✓
    -80
  • D
    160
Answer
Correct option: C.
-80
(C) - $-80$
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MCQ 231 Mark
Which of the following formula is correct for a spherical lens?
  • A
    $\frac{1}{f}=\frac{1}{u}+\frac{1}{v}$
  • ✓
    $\frac{1}{f}=\frac{1}{v}-\frac{1}{u}$
  • C
    $\frac{1}{u}=\frac{1}{v}-\frac{1}{f}$
  • D
    $f=\frac{u v}{u+v}$
Answer
Correct option: B.
$\frac{1}{f}=\frac{1}{v}-\frac{1}{u}$
(B) - $\frac{1}{f}=\frac{1}{v}-\frac{1}{u}$
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MCQ 241 Mark
When a distant object is viewed through an astronomical telescope, its image will be :
  • A
    erect
  • ✓
    inverted
  • C
    distorted
  • D
    none of these
Answer
Correct option: B.
inverted
(B) - inverted
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MCQ 251 Mark
If $\angle i=60^{\circ}$ and $\angle r=90^{\circ}$ then the refractive index ${ }_1 n_2$ will be :
  • ✓
    $\frac{\sqrt{3}}{2}$
  • B
    $\frac{2}{\sqrt{3}}$
  • C
    $\sqrt{3}$
  • D
    $\frac{1}{\sqrt{3}}$
Answer
Correct option: A.
$\frac{\sqrt{3}}{2}$
(A) - $\frac{\sqrt{3}}{2}$
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MCQ 261 Mark
The final image is formed in a compound microscope will be :
  • A
    real and direct
  • ✓
    virtual and inverted
  • C
    virtual and direct
  • D
    real and inverse
Answer
Correct option: B.
virtual and inverted
(B) - virtual and inverted
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MCQ 271 Mark
A light ray incident on a surface of refractive index $n$, which is separating this medium from air. The angle of incidence is $45^{\circ}$. For what value of $n$ can this ray have total internal reflection?
  • A
    $n=1.33$
  • B
    $n=1.40$
  • ✓
    $n=1.50$
  • D
    $n=1.25$
Answer
Correct option: C.
$n=1.50$
(C) - $n=1.50$
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MCQ 281 Mark
For the total internal reflection from any medium to vacuum, critical angle is $30^{\circ}$ then speed of light will be :
  • A
    $3 \times 10^8 m / s$
  • ✓
    $1.5 \times 10^8 m / s$
  • C
    $6 \times 10^8 m / s$
  • D
    $3 \times 10^8 m / s$
Answer
Correct option: B.
$1.5 \times 10^8 m / s$
(B) - $1.5 \times 10^8 m / s$
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MCQ 291 Mark
A concave mirror of focal length f, has formed the image of magnification m, the distance of the object from the mirror is :
  • ✓
    $\frac{(m-1) f}{m}$
  • B
    $\frac{(m+1) f}{m}$
  • C
    $(m-1) f$
  • D
    $(m+1) f$
Answer
Correct option: A.
$\frac{(m-1) f}{m}$
(A) - $\frac{(m-1) f}{m}$
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MCQ 301 Mark
If a ray of light is incident normally on a plane mirror then the value of the angle of reflection is:
  • A
    $90^{\circ}$
  • B
    $180^{\circ}$
  • ✓
    $0^{\circ}$
  • D
    $45^{\circ}$
Answer
Correct option: C.
$0^{\circ}$
(C) $0^{\circ}$
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MCQ 311 Mark
Only paraxial rays are used in image formation by spherical mirror; because this:
  • A
    makes geometry easier.
  • B
    shows minimum deflection.
  • C
    show maximum intensity.
  • ✓
    forms a point image of a point object.
Answer
Correct option: D.
forms a point image of a point object.
(D) - forms a point image of a point object.
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MCQ 321 Mark
The focal length of a concave mirror is 10 cm. On placing an object at 10 cm in front of the mirror, its image will be formed:
  • ✓
    at infinity
  • B
    on the radius of curvature
  • C
    on focus
  • D
    at the pole
Answer
Correct option: A.
at infinity
(A) - at infinity
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MCQ 331 Mark
Which of the following mirrors always forms a virtual and small image?
  • A
    Plane mirror
  • B
    Concave mirror
  • C
    Plane and concave mirror
  • ✓
    Convex mirror
Answer
Correct option: D.
Convex mirror
(D) - Convex mirror
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MCQ 341 Mark
Which of the following mirrors is used in searchlight?
  • ✓
    Concave
  • B
    Plane
  • C
    Convex
  • D
    Cylindrical
Answer
Correct option: A.
Concave
(A) - Concave
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MCQ 351 Mark
The radius of curvature of a concave mirror is 0.80 cm, its focal length in meters will be :
  • ✓
    0.40 meter
  • B
    0.20 meter
  • C
    0.80 meters
  • D
    0.10 meter
Answer
Correct option: A.
0.40 meter
(A) - 0.40 meter
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MCQ 361 Mark
Refraction of light occurs:
  • ✓
    Due to change in the speed of light
  • B
    Due to no change in the speed of light
  • C
    Due to change in color of light
  • D
    Not due to any of the above
Answer
Correct option: A.
Due to change in the speed of light
(A) - Due to change in the speed of light
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MCQ 371 Mark
For which colour, the angle of deviation is maximum when light enters into glass from air?
  • A
    Red
  • B
    Yellow
  • C
    Blue
  • ✓
    Violet
Answer
Correct option: D.
Violet
(D) - Violet
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MCQ 381 Mark
Usually the mirror installed in front of the motor driver's seat is:
  • A
    plane
  • ✓
    convex
  • C
    concave
  • D
    none of these
Answer
Correct option: B.
convex
(B) - convex
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MCQ 391 Mark
A virtual and enlarged image of the object forms:
  • A
    in a convex mirror
  • ✓
    in a concave mirror
  • C
    in a plane mirror
  • D
    none of these
Answer
Correct option: B.
in a concave mirror
(B) - in a concave mirror
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M.C.Q (1 Marks) - Physics STD 12 Science Questions - Vidyadip