JEE Main 2020 (Online) 9th January Evening Slot

In LC circuit the inductance L = 40 mH and
capacitance C = 100 \(\mu\)F. If a voltage
V(t) = 10sin(314t) is applied to the circuit, the
current in the circuit is given as :

The energy required to ionise a hydrogen like
ion in its ground state is 9 Rydbergs. What is
the wavelength of the radiation emitted when
the electron in this ion jumps from the second
excited state to the ground state ?

A particle of mass m is projected with a speed
u from the ground at an angle
\(\theta = {\pi \over 3}\) w.r.t.
horizontal (x-axis). When it has reached its
maximum height, it collides completely
inelastically with another particle of the ...

A rod of length L has non-uniform linear mass
density given by \(\rho\)(x) = \(a + b{\left( {{x \over L}} \right)^2}\)
, where a
and b are constants and 0 \(\le\) x \(\le\) L. The value
of x for the centre of mass of the rod is at :

In a meter bridge experiment S is a standard
resistance. R is a resistance wire. It is found
that balancing length is \(l\) = 25 cm. If R is
replaced by a wire of half length and half
diameter that of R of same material, then the
balancing ...

An electron of mass m and magnitude of charge
|e| initially at rest gets accelerated by a constant
electric field E. The rate of change of de-Broglie
wavelength of this electron at time t ignoring
relativistic effects is :

A plane electromagnetic wave is propagating
along the direction
\({{\widehat i + \widehat j} \over {\sqrt 2 }}\)
, with its polarization
along the direction \(\widehat k\) . The correct form of the
magnetic field of the wave would be (here ...

The circuit shown below is working as a 8 V
dc regulated voltage source. When 12 V is used
as input, the power dissipated (in mW) in each
diode is; (considering both zener diodes are
identical) _________.

Two identical capacitors A and B, charged to
the same potential 5V are connected in two
different circuits as shown below at time t = 0.
If the charge on capacitors A and B at time
t = CR is QA and QB respectively, then (Here
e is the base ...

The current i in the network is :

An electric field \(\overrightarrow E = 4x\widehat i - \left( {{y^2} + 1} \right)\widehat j\) N/C
passes through the box shown in figure. The
flux of the electric field through surfaces ABCD
and BCGF are marked as \({\phi _I}\) and $${\phi...

There is a small source of light at some depth
below the surface of water (refractive
index = \({4 \over 3}\)) in a tank of large cross sectional
surface area. Neglecting any reflection from the
bottom and absorption by water, percentage of...

Planet A has mass M and radius R. Planet B has
half the mass and half the radius of Planet A.
If the escape velocities from the Planets A and
B are vA and vB, respectively, then \({{{v_A}} \over {{v_B}}} = {n \over 4}\).
The value of n is :

Starting at temperature 300 K, one mole of an
ideal diatomic gas (\(\gamma\) = 1.4) is first compressed
adiabatically from volume V1 to V2 = \({{{V_1}} \over {16}}\). It is
then allowed to expand isobarically to volume
2V2. If all the proc...

Two gases-argon (atomic radius 0.07 nm,
atomic weight 40) and xenon (atomic radius
0.1 nm, atomic weight 140) have the same
number density and are at the same
temperature. The raito of their respective mean
free times is closest to :

An electron gun is placed inside a long solenoid
of radius R on its axis. The solenoid has n
turns/length and carries a current I. The
electron gun shoots an electron along the radius
of the solenoid with speed v. If the electron
does not h...

A small circular loop of conducting wire has
radius a and carries current I. It is placed in a
uniform magnetic field B perpendicular to its
plane such that when rotated slightly about its
diameter and released, it starts performing
simple ...

A particle starts from the origin at t = 0 with an
initial velocity of 3.0 \(\widehat i\) m/s and moves in the
x-y plane with a constant acceleration
\(\left( {6\widehat i + 4\widehat j} \right)\) m/s2 . The x-coordinate of the
particle at ...

A small spherical droplet of density d is floating
exactly half immersed in a liquid of density \(\rho\)
and surface tension T. The radius of the droplet
is (take note that the surface tension applies an
upward force on the droplet) :

Two steel wires having same length are
suspended from a ceiling under the same load.
If the ratio of their energy stored per unit
volume is 1 : 4, the ratio of their diameters is:

A uniformly thick wheel with moment of inertia
I and radius R is free to rotate about its centre
of mass (see fig). A massless string is wrapped
over its rim and two blocks of masses m1 and
m2 (m1 \(>\) m2) are attached to the ends of th...

A spring mass system (mass m, spring
constant k and natural length \(l\)) rest in
equilibrium on a horizontal disc. The free end
of the spring is fixed at the centre of the disc.
If the disc together with spring mass system,
rotates about i...

For the four sets of three measured physical
quantities as given below. Which of the
following options is correct ?
(i) A1 = 24.36, B1 = 0.0724, C1 = 256.2
(ii) A2 = 24.44, B2 = 16.082, C2 = 240.2
(iii) A3 = 25.2, B3 = 19.2812, C3 = 236.183...

In a Young's double slit experiment 15 fringes
are observed on a small portion of the screen
when light of wavelength 500 nm is used. Ten
fringes are observed on the same section of
the screen when another light source of
wavelength $$\lamb...

A wire of length L and mass per unit length
6.0 × 10–3 kgm–1 is put under tension of
540 N. Two consecutive frequencies that it
resonates at are : 420 Hz and 490 Hz. Then L
in meters is :