1
JEE Main 2020 (Online) 7th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A litre of dry air at STP expands adiabatically to a volume of 3 litres. If $$\gamma $$ = 1.40, the work done by air is : (31.4 = 4.6555) [Take air to be an ideal gas]
A
60.7 J
B
100.8 J
C
90.5 J
D
48 J
2
JEE Main 2020 (Online) 7th January Morning Slot
Numerical
+4
-0
Change Language
A beam of electromagnetic radiation of intensity 6.4 × 10–5 W/cm2 is comprised of wavelength, $$\lambda $$ = 310 nm. It falls normally on a metal (work function $$\phi $$ = 2eV) of surface area of 1 cm2. If one in 103 photons ejects an elctron, total number of electrons ejected in 1 s is 10x. (hc = 1240 eVnm, 1eV = 1.6 × 10–19 J), then x is _____.
Your input ____
3
JEE Main 2020 (Online) 7th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A LCR circuit behaves like a damped harmonic oscillator. Comparing it with a physical spring-mass damped oscillator having damping constant 'b', the correct equivalence would be:
A
L $$ \leftrightarrow $$ k, C $$ \leftrightarrow $$ b, R $$ \leftrightarrow $$ m
B
L $$ \leftrightarrow $$ m, C $$ \leftrightarrow $$ k, R $$ \leftrightarrow $$ b
C
L $$ \leftrightarrow $$ m, C $$ \leftrightarrow $$ $${1 \over k}$$, R $$ \leftrightarrow $$ b
D
L $$ \leftrightarrow $$ $${1 \over b}$$, C $$ \leftrightarrow $$ $${1 \over m}$$, R $$ \leftrightarrow $$ $${1 \over k}$$
4
JEE Main 2020 (Online) 7th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Three point particles of masses 1.0 kg, 1.5 kg and 2.5 kg are placed at three corners of a right angle triangle of sides 4.0 cm, 3.0 cm and 5.0 cm as shown in the figure. The center of mass of the system is at a point: JEE Main 2020 (Online) 7th January Morning Slot Physics - Center of Mass and Collision Question 76 English
A
2.0 cm right and 0.9 cm above 1 kg mass
B
0.9 cm right and 2.0 cm above 1 kg mass
C
0.6 cm right and 2.0 cm above 1 kg mass
D
1.5 cm right and 1.2 cm above 1 kg mass
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