1
JEE Main 2019 (Online) 10th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
The eye can be regarded as a single refracting surface. The radius of curvature of this surface is equal to that of cornea (7.8 mm). This surface separateds two media of refractive indices 1 and 1.34. Calculate the distance from the refracting surface at which a parallel beam of light will come to focus -
A
2 cm
B
3.1 cm
C
4.0 cm
D
1 cm
2
JEE Main 2019 (Online) 10th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
Consider a Young’s double slit experiment as shown in figure. What should be the slit separation d in terms of wavelength $$\lambda $$ such that the first minima occurs directly in front of the slit (S1) ?

JEE Main 2019 (Online) 10th January Evening Slot Physics - Ray & Wave Optics Question 190 English
A
$${\lambda \over {2\left( {5 - \sqrt 2 } \right)}}$$
B
$${\lambda \over {2\left( {\sqrt 5 - 2} \right)}}$$
C
$${\lambda \over {\left( {5 - \sqrt 2 } \right)}}$$
D
$${\lambda \over {\left( {\sqrt 5 - 2} \right)}}$$
3
JEE Main 2019 (Online) 10th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
In a Young’s double slit experiment with slit separation 0.1 mm, one observes a bright fringe at angle $${1 \over {40}}$$ by using light of wavelength $$\lambda $$1. When the light of wavelength $$\lambda $$2 is used a bright fringe is seen at the same angle in the same set up. Given that $$\lambda $$1 and $$\lambda $$2 are in visible range (380 nm to 740 nm), their values are -
A
400 nm, 500 nm
B
625 nm, 500 nm
C
380 nm, 500 nm
D
380 nm, 525 nm
4
JEE Main 2019 (Online) 10th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
A plano convex lens of refractive index $$\mu $$1 and focal length ƒ1 is kept in contact with another plano concave lens of refractive index $$\mu $$2 and focal length ƒ2. If the radius of curvature of their spherical faces is R each and ƒ1 = 2ƒ2, then $$\mu $$1 and $$\mu $$2 are related as -
A
$$3{\mu _2} - 2{\mu _1}$$ = 1
B
$${\mu _1} + {\mu _2}$$ = 3
C
$$2{\mu _1} - {\mu _2}$$ = 1
D
$$2{\mu _2} - {\mu _1}$$ = 1
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