1
JEE Main 2021 (Online) 31st August Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
The masses and radii of the earth and moon are (M1, R1) and (M2, R2) respectively. Their centres are at a distance 'r' apart. Find the minimum escape velocity for a particle of mass 'm' to be projected from the middle of these two masses :
A
$$V = {1 \over 2}\sqrt {{{4G({M_1} + {M_2})} \over r}} $$
B
$$V = \sqrt {{{4G({M_1} + {M_2})} \over r}} $$
C
$$V = {1 \over 2}\sqrt {{{2G({M_1} + {M_2})} \over r}} $$
D
$$V = {{\sqrt {2G} ({M_1} + {M_2})} \over r}$$
2
JEE Main 2021 (Online) 31st August Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
A small square loop of side 'a' and one turn is placed inside a larger square loop of side b and one turn (b >> a). The two loops are coplanar with their centres coinciding. If a current I is passed in the square loop of side 'b', then the coefficient of mutual inductance between the two loops is :
A
$${{{\mu _0}} \over {4\pi }}8\sqrt 2 {{{a^2}} \over b}$$
B
$${{{\mu _0}} \over {4\pi }}{{8\sqrt 2 } \over a}$$
C
$${{{\mu _0}} \over {4\pi }}8\sqrt 2 {{{b^2}} \over a}$$
D
$${{{\mu _0}} \over {4\pi }}{{8\sqrt 2 } \over b}$$
3
JEE Main 2021 (Online) 31st August Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
Choose the correct waveform that can represent the voltage across R of the following circuit, assuming the diode is ideal one :

JEE Main 2021 (Online) 31st August Morning Shift Physics - Semiconductor Question 81 English
A
JEE Main 2021 (Online) 31st August Morning Shift Physics - Semiconductor Question 81 English Option 1
B
JEE Main 2021 (Online) 31st August Morning Shift Physics - Semiconductor Question 81 English Option 2
C
JEE Main 2021 (Online) 31st August Morning Shift Physics - Semiconductor Question 81 English Option 3
D
JEE Main 2021 (Online) 31st August Morning Shift Physics - Semiconductor Question 81 English Option 4
4
JEE Main 2021 (Online) 31st August Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
A uniform heavy rod of weight 10 kg ms$$-$$2, cross-sectional area 100 cm2 and length 20 cm is hanging from a fixed support. Young modulus of the material of the rod is 2 $$\times$$ 1011 Nm$$-$$2. Neglecting the lateral contraction, find the elongation of rod due to its own weight.
A
2 $$\times$$ 10$$-$$9 m
B
5 $$\times$$ 10$$-$$8 m
C
4 $$\times$$ 10$$-$$8 m
D
5 $$\times$$ 10$$-$$10 m
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