JEE Main 2019 (Online) 8th April Morning Slot

An alternating voltage v(t) = 220 sin 100 \(\pi\)t volt
is applied to a purely resistance load of 50\(\Omega\) .
The time taken for the current to rise from half
of the peak value to the peak value is :

Radiation coming from transitions
n = 2 to n = 1 of hydrogen atoms fall on He+
ions in n = 1 and n = 2 states. The possible
transition of helium ions as they absorb energy
from the radiation is :

Voltage rating of a parallel plate capacitor is
500V. Its dielectric can withstand a maximum
electric field of 106 V/m. The plate area is
10–4 m2. What is the dielectric constant is the
capacitance is 15 pF?
(given \(\varepsilon\)0 = 8.86 ...

If 1022 gas molecules each of mass 10–26 kg
collide with a surface (perpendicular to it)
elastically per second over an area 1 m2 with
a speed 104 m/s, the pressure exerted by the gas
molecules will be of the order of :

Four particles A, B, C and D with masses
mA = m, mB = 2m, mC = 3m and mD = 4m are
at the corners of a square. They have
accelerations of equal magnitude with
directions as shown. The acceleration of the
centre of mass of the particles is :

The wavelength of the carrier waves in a
modern optical fiber communication network
is close to :

A 200 \(\Omega\) resistor has a certain color code. If one
replaces the red color by green in the code, the
new resistance will be :

For the circuit shown, with R1 = 1.0W, R2 = 2.0 W,
E1 = 2 V and E2 = E3 = 4 V, the potential
difference between the points 'a' and 'b' is
approximately (in V):

Two particles move at right angle to each other.
Their de-Broglie wavelengths are \(\lambda _1\) and \(\lambda _2\)
respectively. The particles suffer perfectly
inelastic collision. The de-Broglie wavelength
\(\lambda _2\) of the final part...

A 20 Henry inductor coil is connected to a
10 ohm resistance in series as shown in figure.
The time at which rate of dissipation of energy
(joule's heat) across resistance is equal to the
rate at which magnetic energy is stored in the
induc...

A plane electromagnetic wave travels in free
space along the x-direction. The electric field
component of the wave at a particular point of
space and time is E = 6 V m–1 along y-direction.
Its corresponding magnetic field component,
B would...

The reverse breakdown voltage of a Zener
diode is 5.6 V in the given circuit.
The current IZ through the Zener is :

A solid conducting sphere, having a charge Q,
is surrounded by an uncharged conducting
hollow spherical shell. Let the potential
difference between the surface of the solid
sphere and that of the outer surface of the
hollow shell be V. If t...

The bob of a simple pendulum has mass 2g and
a charge of 5.0 μC. It is at rest in a uniform
horizontal electric field of intensity 2000 V/m.
At equilibrium, the angle that the pendulum
makes with the vertical is : (take g = 10 m/s2)

An upright object is placed at a distance of
40 cm in front of a convergent lens of focal
length 20 cm. A convergent mirror of focal
length 10 cm is placed at a distance of 60 cm
on the other side of the lens. The position and
size of the f...

In figure, the optical fiber is \(l\) = 2m long and
has a diameter of d = 20 μm. If a ray of light
is incident on one end of the fiber at angle
\(\theta _1\) = 40°, the number of reflection it makes
before emerging from the other end is clo...

Four identical particles of mass M are located
at the corners of a square of side 'a'. What
should be their speed if each of them revolves
under the influence of other's gravitational field
in a circular orbit circumscribing the square?

A thermally insulated vessel contains 150g of
water at 0°C. Then the air from the vessel is
pumped out adiabatically. A fraction of water
turns into ice and the rest evaporates at 0°C
itself. The mass of evaporated water will be
closest to ...

Two identical beakers A and B contain equal
volumes of two different liquids at 60°C each
and left to cool down. Liquid in A has density
of 8 × 102 kg/m3 and specific heat of
2000 J kg–1 K–1 while liquid in B has density
of 103 kg m–3 and s...

A circular coil having N turns and radius r
carries a current I. It is held in the XZ plane in
a magnetic field B\({\mathop i\limits^ \wedge }\) . The torque on the coil due
to the magnetic field is :

A thin strip 10 cm long is on a U shaped wire
of negligible resistance and it is connected to
a spring of spring constant 0.5 Nm–1
(see figure). The assembly is kept in a uniform
magnetic field of 0.1 T. If the strip is pulled

from its equ...

Ship A is sailing towards north-east with
velocity \(\mathop v\limits^ \to = 30\mathop i\limits^ \wedge + 50\mathop j\limits^ \wedge\) km/hr where \(\mathop i\limits^ \wedge\) points
east and \(\mathop j\limits^ \wedge\) , north. ...

A boy's catapult is made of rubber cord which
is 42 cm long, with 6 mm diameter of
cross-section and of negligible mass. The boy
keeps a stone weighing 0.02kg on it and
stretches the cord by 20 cm by applying a
constant force. When released...

Water from a pipe is coming at a rate of
100 litres per minute. If the radius of the pipe
is 5 cm, the Reynolds number for the flow is
of the order of : (density of water = 1000 kg/m3,
coefficient of viscosity of water = 1mPas)

A steel wire having a radius of 2.0 mm,
carrying a load of 4 kg, is hanging from a
ceiling. Given that g = 3.1 p ms–2, what will be
the tensile stress that would be developed in the
wire ?

A thin circular plate of mass M and radius R
has its density varying as \(\rho\)(r) = \(\rho\)0r with \(\rho\)0 as
constant and r is the distance from its centre.
The moment of Inertia of the circular plate about
an axis perpendicular to...

In SI units, the dimensions of \(\sqrt {{{{ \in _0}} \over {{\mu _0}}}}\) is :

In an interference experiment the ratio of amplitudes of coherent waves is \({{{a_1}} \over {{a_2}}} = {1 \over 3}\) . The
ratio of maximum and minimum intensities of
fringes will be :

A wire of length 2L, is made by joining two
wires A and B of same length but different radii
r and 2r and made of the same material. It is
vibrating at a frequency such that the joint of
the two wires forms a node. If the number of
antinod...

A particle moves in one dimension from rest
under the influence of a force that varies with
the distance travelled by the particle as shown
in the figure. The kinetic energy of the particle
after it has travelled 3m is :