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JEE Main 2021 (Online) 18th March Evening Shift
MCQ (Single Correct Answer)  +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
2
JEE Main 2021 (Online) 18th March Morning Shift
MCQ (Single Correct Answer)  +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
3
JEE Main 2021 (Online) 18th March Morning Shift
MCQ (Single Correct Answer)  +4  -1
Your friend is having eye sight problem. She is not able to see clearly a distant uniform window mesh and it appears to her as non-uniform and distorted. The doctor diagnosed the problem as :
A
Astigmatism
B
Myopia with Astigmatism
C
Presbyopia with Astigmatism
D
Myopia and Hypermetropia
4
JEE Main 2021 (Online) 17th March Morning Shift
MCQ (Single Correct Answer)  +4  -1
The thickness at the centre of a plane convex lens is 3 mm and the diameter is 6 cm. If the speed of light in the material of the lens is 2 $$\times$$ 108 ms$$-$$1. The focal length of the lens is ____________.
A
0.30 cm
B
30 cm
C
15 cm
D
1.5 cm
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