JEE Main 2020 (Online) 8th January Evening Slot

The first member of the Balmer series of
hydrogen atom has a wavelength of 6561 Å.
The wavelength of the second member of the
Balmer series (in nm) is:

A capacitor is made of two square plates each
of side 'a' making a very small angle \(\alpha\) between
them, as shown in figure. The capacitance will
be close to :

As shown in figure, when a spherical cavity
(centered at O) of radius 1 is cut out of a uniform
sphere of radius R (centered at C), the centre of
mass of remaining (shaded) part of sphere is at
G, i.e, on the surface of the cavity. R can be...

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
inelastic...

The series combination of two batteries, both
of the same emf 10 V, but different internal
resistance of 20\(\Omega\) and 5\(\Omega\), is connected to the
parallel combination of two resistors 30\(\Omega\) and
R \(\Omega\). The voltage ...

A galvanometer having a coil resistance
100 \(\Omega\) gives a full scale deflection when a
current of 1 mA is passed through it. What is
the value of the resistance which can convert
this galvanometer into a voltmeter giving full
scale de...

An electron (mass m) with initial velocity \(\overrightarrow v = {v_0}\widehat i + {v_0}\widehat j\) is in an electric field \(\overrightarrow E = - {E_0}\widehat k\). If \(\lambda _0\) is initial de-Broglie wavelength of electron,
its d...

A shown in the figure, a battery of emf \(\varepsilon\) is
connected to an inductor L and resistance R in
series. The switch is closed at t = 0. The total
charge that flows from the battery, between
t = 0 and t = tc (tc is the time constan...

A plane electromagnetic wave of frequency
25 GHz is propagating in vacuum along the
z-direction. At a particular point in space and
time, the magnetic field is given by \(\overrightarrow B = 5 \times {10^{ - 8}}\widehat jT\). The correspon...

In the given circuit, value of Y is :

A particle of mass m and charge q is released
from rest in a uniform electric field. If there is
no other force on the particle, the dependence
of its speed v on the distance x travelled by it
is correctly given by (graphs are schematic and...

Consider two charged metallic spheres S1 and
S2 of radii R1 and R2, respectively. The electric
fields E1 (on S1) and E2 (on S2) on their surfaces
are such that E1/E2 = R1/R2. Then the ratio
V1 (on S1) / V2 (on S2) of the electrostatic
poten...

An object is gradually moving away from the
focal point of a concave mirror along the axis
of the mirror. The graphical representation of
the magnitude of linear magnification (m)
versus distance of the object from the mirror
(x) is correct...

An asteroid is moving directly towards the
centre of the earth. When at a distance of
10R (R is the radius of the earth) from the earths
centre, it has a speed of 12 km/s. Neglecting
the effect of earths atmosphere, what will be the
speed o...

A ball is dropped from the top of a 100 m high
tower on a planet. In the last \({1 \over 2}s\) before hitting
the ground, it covers a distance of 19 m.
Acceleration due to gravity (in ms–2) near the
surface on that planet is _____.

Three containers C1, C2 and C3 have water at
different temperatures. The table below shows
the final temperature T when different amounts
of water (given in litres) are taken from each
containers and mixed (assume no loss of heat
during the...

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 :

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 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...

A particle moves such that its position
vector \(\overrightarrow r \left( t \right) = \cos \omega t\widehat i + \sin \omega t\widehat j\) where \(\omega\) is a constant and t is time. Then which of the following statements is true for the ...

Two liquids of densities \({\rho _1}\) an \({\rho _2}\) (\({\rho _2}\) = 2\({\rho _1}\)) are
filled up behind a square wall of side 10 m as
shown in figure. Each liquid has a height of
5 m. The ratio of the forces due to these liquids
exert...

A uniform sphere of mass 500 g rolls without
slipping on a plane horizontal surface with its
centre moving at a speed of 5.00 cm/s. Its
kinetic energy is :

A simple pendulum is being used to determine
th value of gravitational acceleration g at a
certain place. Th length of the pendulum is
25.0 cm and a stop watch with 1s resolution
measures the time taken for 40 oscillations to
be 50 s. The a...

In a double slit experiment, at a certain point
on the screen the path difference between the
two interfering waves is \({1 \over 8}\)th of a wavelength.
The ratio of the intensity of light at that point
to that at the centre of a bright fr...

A transverse wave travels on a taut steel wire
with a velocity of v when tension in it is
2.06 × 104 N. When the tension is changed to
T, the velocity changed to v/2. The value of T
is close to :