1
JEE Main 2021 (Online) 20th July Evening Shift
+4
-1
With what speed should a galaxy move outward with respect to earth so that the sodium-D line at wavelength 5890 $$\mathop A\limits^o$$ is observed at 5896 $$\mathop A\limits^o$$ ?
A
306 km/sec
B
322 km/sec
C
296 km/sec
D
336 km/sec
2
JEE Main 2021 (Online) 20th July Morning Shift
+4
-1
Region I and II are separated by a spherical surface of radius 25 cm. An object is kept in region I at a distance of 40 cm from the surface. The distance of the image from the surface is :

A
55.44 cm
B
18.23 cm
C
9.52 cm
D
37.58 cm
3
JEE Main 2021 (Online) 18th March Evening Shift
+4
-1
Three rays of light, namely red (R), green (G) and blue (B) are incident on the face PQ of a right angled prism PQR as shown in the figure.

The refractive indices of the material of the prism for red, green and blue wavelength are 1.27, 1.42 and 1.49 respectively. The colour of the ray(s) emerging out of the face PR is :
A
green
B
blue and green
C
blue
D
red
4
JEE Main 2021 (Online) 18th March Morning Shift
+4
-1
In Young's double slit arrangement, slits are separated by a gap of 0.5 mm, and the screen is placed at a distance of 0.5 m from them. The distance between the first and the third bright fringe formed when the slits are illuminated by a mnochromatic light of 5890 $$\mathop A\limits^o$$ is :-
A
1178 $$\times$$ 10$$-$$9 m
B
1178 $$\times$$ 10$$-$$6 m
C
1178 $$\times$$ 10$$-$$12 m
D
5890 $$\times$$ 10$$-$$7 m
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