1
JEE Main 2021 (Online) 27th July Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
Two identical particles of mass 1 kg each go round a circle of radius R, under the action of their mutual gravitational attraction. The angular speed of each particle is :
A
$$\sqrt {{G \over {2{R^3}}}} $$
B
$${1 \over 2}\sqrt {{G \over {{R^3}}}} $$
C
$${1 \over {2R}}\sqrt {{1 \over G}} $$
D
$${{2G} \over {{R^3}}}$$
2
JEE Main 2021 (Online) 27th July Evening Shift
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
Change Language
Consider the following statements :

A. Atoms of each element emit characteristics spectrum.

B. According to Bohr's Postulate, an electron in a hydrogen atom, revolves in a certain stationary orbit.

C. The density of nuclear matter depends on the size of the nucleus.

D. A free neutron is stable but a free proton decay is possible.

E. Radioactivity is an indication of the instability of nuclei.

Choose the correct answer from the options given below :
A
A, B, C, D and E
B
A, B and E only
C
B and D only
D
A, C and E only
3
JEE Main 2021 (Online) 27th July Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
What will be the magnitude of electric field at point O as shown in the figure? Each side of the figure is l and perpendicular to each other?

JEE Main 2021 (Online) 27th July Evening Shift Physics - Electrostatics Question 88 English
A
$${1 \over {4\pi {\varepsilon _0}}}{q \over {{l^2}}}$$
B
$${1 \over {4\pi {\varepsilon _0}}}{q \over {(2{l^2})}}\left( {2\sqrt 2 - 1} \right)$$
C
$${q \over {4\pi {\varepsilon _0}{{(2l)}^2}}}$$
D
$${1 \over {4\pi {\varepsilon _0}}}{{2q} \over {2{l^2}}}\left( {\sqrt 2 } \right)$$
4
JEE Main 2021 (Online) 27th July Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
A physical quantity 'y' is represented by the formula $$y = {m^2}{r^{ - 4}}{g^x}{l^{ - {3 \over 2}}}$$

If the percentage errors found in y, m, r, l and g are 18, 1, 0.5, 4 and p respectively, then find the value of x and p.
A
5 and $$\pm$$2
B
4 and $$\pm$$3
C
$${{16} \over 3}$$ and $$ \pm {3 \over 2}$$
D
8 and $$\pm$$ 2
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