JEE Main 2020 Physics Paper: 4 Sep, Shift 1

In the line spectra of hydrogen atoms, difference between the largest and the shortest wavelengths ${}$ of the Lyman series is 304 $\text{Å}$. The corresponding difference for the Paschan series in $\text{Å}$ is: ___________.

A battery of 3.0 V is connected to a resistor dissipating 0.5 W of power. If the terminal voltage of the battery is 2.5 V, the power dissipated within the internal resistance is:

Particle A of mass mA = $\frac{m}{2}$ moving along the x-axis with velocity v0 collides elastically with another particle B at rest having mass mB = $\frac{m}{3}$. If both particles move along the x-axis after the collision, the change $\Delta\lambda$ in de-Broglie wavlength of particle A, in terms of its de-Broglie wavelength ($\lambda$0) before collision is:

Given figure shows few data points in a photoelectric effect experiment for a certain metal. The minimum energy for ejection of electron from its surface is:

(Planck's constant h = 6.62 × 10–34 J.s)

A small bar magnet is moved through a coil at constant speed from one end to the other. Which of the following series of observations will be seen on the galvanometer G attached across the coil?

Three positions shown describe:

(a) the magnet's entry

(b) magnet is completely inside and

(c) magnet's exit.

Choose the correct option relating wave lengths of different parts of electromagnetic wave spectrum:

Two charged thin infinite plane sheets of

uniform surface charge density $\sigma_{+}$ and $\sigma_{-}$,

where |$\sigma_{+}$| > |$\sigma_{-}$ |, intersect at right angle.

Which of the following best represents the

electric field lines for this system:

A two point charges 4q and -q are fixed on the x-axis at x = $-\frac{d}{2}$ and x = $\frac{d}{2}$ respectively. If a third point charge 'q' is taken from the origin to x = d along the semicircle as shown in the figure, the energy of the charge will:

A air bubble of radius 1 cm in water has an upward acceleration 9.8 cm s–2. The density of water is 1 gm cm–3 and water offers negligible drag force on the bubble. The mass of the bubble is (g = 980 cm/s2).

On the x-axis and at a distance x from the origin, the gravitational field due a mass distribution is given by $\frac{Ax}{(x^2+a^2)^{3/2}}$ in the x-direction. The magnitude of gravitational potential on the x-axis at a distance x, taking its value to be zero at infinity, is:

A small bar magnet placed with its axis

at 30° with an external field of 0.06 T

experiences a torque of 0.018 Nm. The

minimum work required to rotate it from its

stable to unstable equilibrium position is:

A Tennis ball is released from a height h and after freely falling on a wooden floor it rebounds and reaches height $\frac{h}{2}$. The velocity versus height of the ball during its motion may be represented graphically by:

(graph are drawn schematically and on not to scale)

A wire A, bent in the shape of an arc of a circle, carrying a current of 2 A and having radius 2 cm and another wire B, also bent in the shape of arc of a circle, carrying a current of 3 A and having radius of 4 cm, are placed as shown in the figure. The ratio of the magnetic fields due to the wires A and B at the common centre O is:

Starting from the origin at time t = 0, with initial velocity 5$\hat{j}$ ms-1, a particle moves in the x-y plane with a constant acceleration of $\left(10\hat{i} + 4\hat{j}\right)$ ms-2. At time t, its coordinates are (20 m, y0 m). The values of t and y0 are, respectively:

In a compound microscope, the magnified virtual image is formed at a distance of 25 cm from the eye-piece. The focal length of its objective lens is 1 cm. If the magnification is 100 and the tube length of the microscope is 20 cm, then the focal length of the eye-piece lens (in cm) is __________.

A circular disc of mass M and radius R is rotating about its axis with angular speed $\omega_1$. If another stationary disc having radius $\frac{R}{2}$ and same mass M is dropped co-axially on to the rotating disc. Gradually both discs attain constant angular speed $\omega_2$ the energy lost in the process is p% of the initial energy. Value of p is __________.

ABC is a plane lamina of the shape of an equilateral triangle. D, E are mid points of AB, AC and G is the centroid of the lamina. Moment of inertia of the lamina about an axis passing through G and perpendicular to the plane ABC is I0. If part ADE is removed, the moment of inertia of the remaining part about the same axis is $\frac{NI_0}{16}$ where N is an integer. Value of N is ______.

Take the breakdown voltage of the

zener diode used in the given circuit as 6V.

For the input voltage shown in figure below,

the time variation of the output voltage is:

(Graphs drawn are schematic and not to scale)

A closed vessel contains 0.1 mole of a monoatomic ideal gas at 200 K. If 0.05 mole of the same gas at 400 K is added to it, the final equilibrium temperature (in K) of the gas in the vessel will be close to _______.

Match the $\frac{C_P}{C_V}$ ratio for ideal gases with different type of molecules:

The specific heat of water

= 4200 J kg-1K-1 and the latent heat of

ice = 3.4 $\times$ 105 J kg–1. 100 grams of ice at

0oC is placed in 200 g of water at 25oC. The

amount of ice that will melt as the temperature

of water reaches 0oC is close to (in grams):

Dimensional formula for thermal conductivity is (here K denotes the temperature):

For a transverse wave travelling along a straight line, the distance between two peaks (crests) is 5 m, while the distance between one crest and one trough is 1.5 m. The possible wavelengths (in m) of the wave are:

A beam of plane polarised light of large

cross-sectional area and uniform intensity

of 3.3 Wm-2 falls normally on a

polariser (cross sectional area 3 $\times$ 10-4 m2) which

rotates about its axis with an angular speed

of 31.4 rad/s. The energy of light passing through

the polariser per revolution, is close to: