1
JEE Main 2020 (Online) 3rd September Morning Slot
Numerical
+4
-0
An observer can see through a small hole on the side of a jar (radius 15 cm) at a point at height of 15 cm from the bottom (see figure). The hole is at a height of 45 cm. When the jar is filled with a liquid up to a height of 30 cm the same observer can see the edge at the bottom of the jar. If the refractive index of the liquid is N/100, where N is an integer, the value of N is _____.
2
JEE Main 2020 (Online) 2nd September Evening Slot
Numerical
+4
-0
A light ray enters a solid glass sphere of refractive index $$\mu$$ = $$\sqrt 3$$ at an angle of incidence 60o. The ray is both reflected and refracted at the farther surface of the sphere. The angle (in degrees) between the reflected and refracted rays at this surface is ________.
3
JEE Main 2020 (Online) 9th January Evening Slot
Numerical
+4
-0
In a Young's double slit experiment 15 fringes are observed on a small portion of the screen when light of wavelength 500 nm is used. Ten fringes are observed on the same section of the screen when another light source of wavelength $$\lambda$$ is used. Then the value of $$\lambda$$ is (in nm) __________.
4
JEE Main 2020 (Online) 8th January Morning Slot
Numerical
+4
-0
A point object in air is in front of the curved surface of a plano-convex lens. The radius of curvature of the curved surface is 30 cm and the refractive index of the lens material is 1.5, then the focal length of the lens (in cm) is ______.
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