1
JEE Main 2019 (Online) 8th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
In figure, the optical fiber is $$l$$ = 2m long and has a diameter of d = 20 μm. If a ray of light is incident on one end of the fiber at angle $$\theta _1$$ = 40°, the number of reflection it makes before emerging from the other end is close to: (refractive index of fibre is 1.31 and sin 40° = 0.64) JEE Main 2019 (Online) 8th April Morning Slot Physics - Geometrical Optics Question 136 English
A
57000
B
55000
C
66000
D
45000
2
JEE Main 2019 (Online) 12th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A plano-convex lens (focal length f2, refractive index $$\mu $$2, radius of curvature R) fits exactly into a plano-concave lens (focal length f1, refractive index $$\mu $$1, radius of curvature R). Their plane surfaces are parallel to each other. Then, the focal length of the combination will be :
A
f1 + f2
B
f1 $$-$$ f2
C
$${R \over {{\mu _2} - {\mu _1}}}$$
D
$${{2{f_1}{f_2}} \over {{f_1} + {f_2}}}$$
3
JEE Main 2019 (Online) 12th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Formation of real image using a biconvex lens is shown below :

JEE Main 2019 (Online) 12th January Evening Slot Physics - Geometrical Optics Question 138 English

If the whole set up is immersed in water without disturbing the object and the screen positions, what will one observe on the screen ?
A
Image disappears
B
Magnified image
C
Erect real image
D
No change
4
JEE Main 2019 (Online) 12th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A point source of light, S is placed at distance L in front of the centre of plane mirror of width d which is hanging vertically on a wall. A man walks in front of the mirror along a line parallel to the mirror, at a distance 2L as shown below. The distance over which the man can see the image of the light source in the mirror is

JEE Main 2019 (Online) 12th January Morning Slot Physics - Geometrical Optics Question 141 English
A
d
B
d/2
C
3d
D
2d
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