1
JEE Main 2020 (Online) 8th January Evening Slot
+4
-1
In a double slit experiment, at a certain point on the screen the path difference between the two interfering waves is $${1 \over 8}$$th of a wavelength. The ratio of the intensity of light at that point to that at the centre of a bright fringe is :
A
0.853
B
0.568
C
0.672
D
0.760
2
JEE Main 2020 (Online) 8th January Evening Slot
+4
-1
An object is gradually moving away from the focal point of a concave mirror along the axis of the mirror. The graphical representation of the magnitude of linear magnification (m) versus distance of the object from the mirror (x) is correctly given by :
(Graphs are drawn schematically and are not to scale)
A
B
C
D
3
JEE Main 2020 (Online) 8th January Morning Slot
+4
-1
The magnifying power of a telescope with tube 60 cm is 5. What is the focal length of its eye piece ?
A
40 cm
B
10 cm
C
30 cm
D
20 cm
4
JEE Main 2020 (Online) 8th January Morning Slot
+4
-1
The critical angle of a medium for a specific wavelength, if the medium has relative permittivity 3 and relative permeability $${4 \over 3}$$ for this wavelength, will be :
A
45°
B
15°
C
30°
D
60°
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