1
JEE Main 2018 (Online) 15th April Morning Slot
+4
-1
Light of wavelength $$550$$ $$nm$$ falls normally on a slit of width $$22.0 \times {10^{ - 5}}$$ $$cm.$$ The angular position of the second minima from the central maximum will (in radians) :
A
$${\pi \over {12}}$$
B
$${\pi \over 8}$$
C
$${\pi \over 6}$$
D
$${\pi \over 4}$$
2
JEE Main 2018 (Online) 15th April Morning Slot
+4
-1
A planoconvex lens becomes an optical system of $$28$$ $$cm$$ focal length when its plane surface is silvered and illuminated from left to right as shown in Fig-A.

If the same lens is instead silvered on the curved surface and illuminated from other side as in Fig-B, it acts like an optical system of focal length $$10$$ $$cm.$$ The refractive index of the material of lens is :

A
$$1.50$$
B
$$1.55$$
C
$$1.75$$
D
$$1.51$$
3
JEE Main 2018 (Online) 15th April Morning Slot
+4
-1
A particle is oscillating on the $$X$$-axis with an amplitude $$2$$ $$cm$$ about the point $${x_0} = 10\,cm,$$ with a frequency $$\omega$$. A concave mirror of local length $$5$$cm$$is placed at the origin (see figure). Identify the correct statements. A The image executs periodic motoin. B The image executes non-periodic motion. C The turning points of the image are asymmetric w.r.t. the image of the point at$$x=10cm$$. D The distance between the turning points of the oscillation of the image is$${{100} \over {21}}\,cm.
4
JEE Main 2017 (Online) 9th April Morning Slot
+4
-1
In an experiment a convex lens of focal length 15 cm is placed coaxially on an optical bench in front of a convex mirror at a distance of 5 cm from it. It is found that an object and its image coincide, if the object is placed at a distance of 20 cm from the lens. The focal length of the convex mirror is :
A
27.5 cm
B
20.0 cm
C
25.0 cm
D
30.5 cm
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