1
JEE Main 2021 (Online) 27th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
The relative permittivity of distilled water is 81. The velocity of light in it will be :

(Given $$\mu$$r = 1)
A
4.33 $$\times$$ 107 m/s
B
2.33 $$\times$$ 107 m/s
C
3.33 $$\times$$ 107 m/s
D
5.33 $$\times$$ 107 m/s
2
JEE Main 2021 (Online) 27th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
List-I List-II
(a) MI of the rod (length L, Mass M, about an axis $$ \bot $$ to the rod passing through the midpoint) (i) $$8M{L^2}/3$$
(b) MI of the rod (length L, Mass 2M, about an axis $$ \bot $$ to the rod passing through one of its end) (ii) $$M{L^2}/3$$
(c) MI of the rod (length 2L, Mass M, about an axis $$ \bot $$ to the rod passing through its midpoint) (iii) $$M{L^2}/12$$
(d) MI of the rod (Length 2L, Mass 2M, about an axis $$ \bot $$ to the rod passing through one of its end) (iv) $$2M{L^2}/3$$


Choose the correct answer from the options given below:
A
(a)-(ii), (b)-(iii), (c)-(i), (d)-(iv)
B
(a)-(ii), (b)-(i), (c)-(iii), (d)-(iv)
C
(a)-(iii), (b)-(iv), (c)-(ii), (d)-(i)
D
(a)-(iii), (b)-(iv), (c)-(i), (d)-(ii)
3
JEE Main 2021 (Online) 27th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
Three objects A, B and C are kept in a straight line on a frictionless horizontal surface. The masses of A, B and C are m, 2m and 2m respectively. A moves towards B with a speed of 9 m/s and makes an elastic collision with it. Thereafter B makes a completely inelastic collision with C. All motions occur along same straight line. The final speed of C is :

JEE Main 2021 (Online) 27th July Morning Shift Physics - Center of Mass and Collision Question 37 English
A
6 m/s
B
9 m/s
C
4 m/s
D
3 m/s
4
JEE Main 2021 (Online) 27th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
JEE Main 2021 (Online) 27th July Morning Shift Physics - Capacitor Question 63 English
A capacitor of capacitance C = 1 $$\mu$$F is suddenly connected to a battery of 100 volt through a resistance R = 100 $$\Omega$$. The time taken for the capacitor to be charged to get 50 V is :

[Take ln 2 = 0.69]
A
1.44 $$\times$$ 10$$-$$4 s
B
3.33 $$\times$$ 10$$-$$4 s
C
0.69 $$\times$$ 10$$-$$4 s
D
0.30 $$\times$$ 10$$-$$4 s
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