1
JEE Main 2020 (Online) 8th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A very long wire ABDMNDC is shown in figure carrying current I. AB and BC parts are straight, long and at right angle. At D wire forms a circular turn DMND of radius R. AB, BC parts are tangential to circular turn at N and D. Magnetic field at the centre of circle is : JEE Main 2020 (Online) 8th January Evening Slot Physics - Magnetic Effect of Current Question 112 English
A
$${{{\mu _0}I} \over {2\pi R}}\left( {\pi + 1} \right)$$
B
$${{{\mu _0}I} \over {2\pi R}}\left( {\pi - {1 \over {\sqrt 2 }}} \right)$$
C
$${{{\mu _0}I} \over {2R}}$$
D
$${{{\mu _0}I} \over {2\pi R}}\left( {\pi + {1 \over {\sqrt 2 }}} \right)$$
2
JEE Main 2020 (Online) 8th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A particle of mass m is dropped from a height h above the ground. At the same time another particle of the same mass is thrown vertically upwards from the ground with a speed of $$\sqrt {2gh} $$. If they collide head-on completely inelastically, the time taken for the combined mass to reach the ground, in units of $$\sqrt {{h \over g}} $$ is :
A
$$\sqrt {{1 \over 2}} $$
B
$${1 \over 2}$$
C
$$\sqrt {{3 \over 2}} $$
D
$$\sqrt {{3 \over 4}} $$
3
JEE Main 2020 (Online) 8th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
Change Language
A carnot engine having an efficiency of $${1 \over {10}}$$ is being used as a refrigerator. If the work done on the refrigerator is 10 J, the amount of heat absorbed from the reservoir at lower temperature is :
A
90 J
B
99 J
C
1 J
D
100 J
4
JEE Main 2020 (Online) 8th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Consider a mixture of n moles of helium gas and 2n moles of oxygen gas (molecules taken to be rigid) as an ideal gas. Its CP/CV value will be :
A
23/15
B
67/45
C
40/27
D
19/13
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