JEE Main 2020 (Online) 3rd September Evening Slot

The radius R of a nucleus of mass number A can be estimated by the formula R = (1.3 \(\times\) 10–15)A1/3 m.
It follows that the mass density of a nucleus is of the order of :
(Mprot. \(\cong\) Mneut \(\simeq\) 1.67 \(\times\) 10–27...

Hydrogen ion and singly ionized helium atom are accelerated, from rest, through the same potential
difference. The ratio of final speeds of hydrogen and helium ions is close to :

A block of mass 1.9 kg is at rest at the edge of a table, of height 1 m. A bullet of mass 0.1 kg
collides with the block and sticks to it. If the velocity of the bullet is 20 m/s in the horizontal
direction just before the collision then th...

Two resistors 400\(\Omega\) and 800\(\Omega\) are connected in series across a 6 V battery. The potential difference measured by a voltmeter of 10 k\(\Omega\) across 400 \(\Omega\) resistor is close to :

Two sources of light emit X-rays of wavelength 1 nm and visible light of wavelength 500 nm, respectively. Both the sources emit light of the same power 200 W. The ratio of the number density of
photons of X-rays to the number density of pho...

A uniform magnetic field B exists in a direction perpendicular to the plane of a square loop made of
a metal wire. The wire has a diameter of 4 mm and a total length of 30 cm. The magnetic field
changes with time at a steady rate $${{dB} \o...

The electric field of a plane electromagnetic wave propagating along the x direction in vacuum is
\(\overrightarrow E = {E_0}\widehat j\cos \left( {\omega t - kx} \right)\).
The magnetic field \(\overrightarrow B\)
, at the moment t = 0 ...

If a semiconductor photodiode can detect a photon with a maximum wavelength of 400 nm, then
its band gap energy is :
Planck’s constant h = 6.63 \(\times\) 10–34 J.s. Speed of light c = 3 \(\times\) 108
m/s

Which of the following will NOT be observed when a multimeter (operating in resistance measuring
mode) probes connected across a component, are just reversed?

Concentric metallic hollow spheres of radii R and 4R hold charges Q1
and Q2
respectively. Given that
surface charge densities of the concentric spheres are equal, the potential difference V(R) – V(4R) is :

When an object is kept at a distance of 30 cm from a concave mirror, the image is formed at a
distance of 10 cm from the mirror. If the object is moved with a speed of 9 cms–1, the speed
(in cms–1) with which image moves at that instant is ...

The mass density of a planet of radius R varies with the distance r from its centre as
\(\rho\)(r) = \({\rho _0}\left( {1 - {{{r^2}} \over {{R^2}}}} \right)\).
Then the gravitational field is maximum at :

To raise the temperature of a certain mass of gas by 50oC at a constant pressure, 160 calories of
heat is required. When the same mass of gas is cooled by 100oC at constant volume, 240 calories
of heat is released. How many degrees of freed...

If minimum possible work is done by a refrigerator in converting 100 grams of water at 0oC to ice,
how much heat (in calories) is released to the surroundings at temperature 27oC (Latent heat of
ice = 80 Cal/gram) to the nearest integer ?

A calorimeter of water equivalent 20 g contains 180 g of water at 25oC. ‘m’ grams of steam at
100oC is mixed in it till the temperature of the mixure is 31oC. The value of ‘m’ is close to :(Latent
heat of water = 540 cal g–1, specific heat ...

A perfectly diamagnetic sphere has a small spherical cavity at its centre, which is filled with a
paramagnetic substance. The whole system is placed in a uniform magnetic field \(\overrightarrow B\)
. Then the field
inside the paramagnetic...

A galvanometer coil has 500 turns and each turn has an average area of 3 \(\times\) 10–4 m2
. If a torque of
1.5 Nm is required to keep this coil parallel to a magnetic field when a current of 0.5 A is flowing
through it, the strength of ...

A metallic sphere cools from 50oC to 40o in 300 s. If atmospheric temperature around is 20oC,
then the sphere’s temperature after the next 5 minutes will be close to :

A uniform rod of length ‘\(l\)’ is pivoted at one of its ends on a vertical shaft of negligible radius.
When the shaft rotates at angular speed \(\omega\) the rod makes an angle \(\theta\) with it (see figure). To find \(\theta\)
equate ...

An massless equilateral triangle EFG of side ‘a’ (As shown in figure) has three particles of mass m
situated at its vertices. The moment of inertia of the system about the line EX perpendicular to EG
in the plane of EFG is $${N \over {20}}$...

A block of mass m attached to a massless spring is performing oscillatory motion of amplitude ‘A’ on
a frictionless horizontal plane. If half of the mass of the block breaks off when it is passing through
its equilibrium point, the amplitud...

Amount of solar energy received on the earth’s surface per unit area per unit time is defined a solar
constant. Dimension of solar constant is :

Two light waves having the same wavelength \(\lambda\) in vacuum are in phase initially. Then the first wave
travels a path L1
through a medium of refractive index n1
while the second wave travels a path of length
L2
through a medium of...

A block starts moving up an inclined plane of inclination 30o with an initial velocity of v0
. It comes
back to its initial position with velocity \({{{v_0}} \over 2}\). The value of the coefficient of kinetic friction between
the block and...

A particle is moving unidirectionally on a horizontal plane under the action of a constant power
supplying energy source. The displacement (s) - time (t) graph that describes the motion of the
particle is (graphs are drawn schematically and...