1
JEE Main 2021 (Online) 31st August Morning Shift
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
Change Language
A sample of a radioactive nucleus A disintegrates to another radioactive nucleus B, which in turn disintegrates to some other stable nucleus C. Plot of a graph showing the variation of number of atoms of nucleus B versus time is :

(Assume that at t = 0, there are no B atoms in the sample)
A
JEE Main 2021 (Online) 31st August Morning Shift Physics - Atoms and Nuclei Question 103 English Option 1
B
JEE Main 2021 (Online) 31st August Morning Shift Physics - Atoms and Nuclei Question 103 English Option 2
C
JEE Main 2021 (Online) 31st August Morning Shift Physics - Atoms and Nuclei Question 103 English Option 3
D
JEE Main 2021 (Online) 31st August Morning Shift Physics - Atoms and Nuclei Question 103 English Option 4
2
JEE Main 2021 (Online) 31st August Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
A coil having N turns is wound tightly in the form of a spiral with inner and outer radii 'a' and 'b' respectively. Find the magnetic field at centre, when a current I passes through coil:
A
$${{{\mu _0}IN} \over {2(b - a)}}{\log _e}\left( {{b \over a}} \right)$$
B
$${{{\mu _0}I} \over 8}\left[ {{{a + b} \over {a - b}}} \right]$$
C
$${{{\mu _0}I} \over {4(a - b)}}\left[ {{1 \over a} - {1 \over b}} \right]$$
D
$${{{\mu _0}I} \over 8}\left( {{{a - b} \over {a + b}}} \right)$$
3
JEE Main 2021 (Online) 31st August Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
A body of mass M moving at speed V0 collides elastically with a mass 'm' at rest. After the collision, the two masses move at angles $$\theta$$1 and $$\theta$$2 with respect to the initial direction of motion of the body of mass M. The largest possible value of the ratio M/m, for which the angles $$\theta$$1 and $$\theta$$2 will be equal, is :
A
4
B
1
C
3
D
2
4
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
$$V = {{\sqrt {2G} ({M_1} + {M_2})} \over r}$$
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