JEE MAIN - Physics (2024 - 6th April Morning Shift)

1
A bullet of mass $$50 \mathrm{~g}$$ is fired with a speed $$100 \mathrm{~m} / \mathrm{s}$$ on a plywood and emerges with $$40 \mathrm{~m} / \mathrm{s}$$. The percentage loss of kinetic energy is :
Răspuns
(C)
$$84 \%$$
2
The specific heat at constant pressure of a real gas obeying $$P V^2=R T$$ equation is:
Răspuns
(C)
$$C_V+\frac{R}{2 V}$$
3
The correct truth table for the following logic circuit is :

Răspuns
(B)
4
Electromagnetic waves travel in a medium with speed of $$1.5 \times 10^8 \mathrm{~m} \mathrm{~s}^{-1}$$. The relative permeability of the medium is 2.0. The relative permittivity will be:
Răspuns
(C)
2
5
To find the spring constant $$(k)$$ of a spring experimentally, a student commits $$2 \%$$ positive error in the measurement of time and $$1 \%$$ negative error in measurement of mass. The percentage error in determining value of $$k$$ is :
Răspuns
(A)
5%
6
The value of unknown resistance $$(x)$$ for which the potential difference between $$B$$ and $$D$$ will be zero in the arrangement shown, is :

Răspuns
(C)
6 $$\Omega$$
7
A light string passing over a smooth light pulley connects two blocks of masses $$m_1$$ and $$m_2\left(\right.$$ where $$\left.m_2>m_1\right)$$. If the acceleration of the system is $$\frac{g}{\sqrt{2}}$$, then the ratio of the masses $$\frac{m_1}{m_2}$$ is:
Răspuns
(C)
$$\frac{\sqrt{2}-1}{\sqrt{2}+1}$$
8
To project a body of mass $$m$$ from earth's surface to infinity, the required kinetic energy is (assume, the radius of earth is $$R_E, g=$$ acceleration due to gravity on the surface of earth):
Răspuns
(C)
$$m g R_E$$

Match List I with List II

	LIST I		LIST II
A.	Torque	I.	$$ \left[M^1 L^1 T^{-2} A^{-2}\right] $$
B.	Magnetic field	II.	$$ \left[L^2 A^1\right] $$
C.	Magnetic moment	III.	$$ \left[M^1 T^{-2} A^{-1}\right] $$
D.	Permeability of free space	IV.	$$ \left[M^1 L^2 T^{-2}\right] $$

Choose the correct answer from the options given below:

Răspuns

(D)

A-IV, B-III, C-II, D-I

10
Which of the following phenomena does not explain by wave nature of light.

A. reflection

B. diffraction

C. photoelectric effect

D. interference

E. polarization

Choose the most appropriate answer from the options given below:
Răspuns
(A)
C only
11
Four particles $$A, B, C, D$$ of mass $$\frac{m}{2}, m, 2 m, 4 m$$, have same momentum, respectively. The particle with maximum kinetic energy is :
Răspuns
(D)
A
12
In photoelectric experiment energy of $$2.48 \mathrm{~eV}$$ irradiates a photo sensitive material. The stopping potential was measured to be $$0.5 \mathrm{~V}$$. Work function of the photo sensitive material is :
Răspuns
(A)
1.98 eV
13
While measuring diameter of wire using screw gauge the following readings were noted. Main scale reading is $$1 \mathrm{~mm}$$ and circular scale reading is equal to 42 divisions. Pitch of screw gauge is $$1 \mathrm{~mm}$$ and it has 100 divisions on circular scale. The diameter of the wire is $$\frac{x}{50} \mathrm{~mm}$$. The value of $$x$$ is :
Răspuns
(B)
71
14
Given below are two statements :

Statement I : In an LCR series circuit, current is maximum at resonance.

Statement II : Current in a purely resistive circuit can never be less than that in a series LCR circuit when connected to same voltage source.

In the light of the above statements, choose the correct from the options given below :
Răspuns
(C)
Both Statement I and Statement II are true
15
$$\sigma$$ is the uniform surface charge density of a thin spherical shell of radius R. The electric field at any point on the surface of the spherical shell is :
Răspuns
(B)
$$\sigma / \in_o$$
16
An element $$\Delta l=\Delta x\hat{i}$$ is placed at the origin and carries a large current $$I=10 \mathrm{~A}$$. The magnetic field on the $$y$$-axis at a distance of $$0.5 \mathrm{~m}$$ from the elements $$\Delta x$$ of $$1 \mathrm{~cm}$$ length is:

Răspuns
(C)
$$4 \times 10^{-8} \mathrm{~T}$$
17
A small ball of mass $$m$$ and density $$\rho$$ is dropped in a viscous liquid of density $$\rho_0$$. After sometime, the ball falls with constant velocity. The viscous force on the ball is :
Răspuns
(A)
$$m g\left(1-\frac{\rho_0}{\rho}\right)$$
18
A train starting from rest first accelerates uniformly up to a speed of $$80 \mathrm{~km} / \mathrm{h}$$ for time $$t$$, then it moves with a constant speed for time $$3 t$$. The average speed of the train for this duration of journey will be (in $$\mathrm{km} / \mathrm{h}$$) :
Răspuns
(A)
70
19
A sample contains mixture of helium and oxygen gas. The ratio of root mean square speed of helium and oxygen in the sample, is :
Răspuns
(C)
$$\frac{2 \sqrt{2}}{1}$$
20
The ratio of the shortest wavelength of Balmer series to the shortest wavelength of Lyman series for hydrogen atom is :
Răspuns
(D)
$$4: 1$$
21
A big drop is formed by coalescing 1000 small droplets of water. The ratio of surface energy of 1000 droplets to that of energy of big drop is $$\frac{10}{x}$$. The value of $$x$$ is ________.
Răspuns
1
22
If the radius of earth is reduced to three-fourth of its present value without change in its mass then value of duration of the day of earth will be ________ hours 30 minutes.
Răspuns
13
23
A particle is doing simple harmonic motion of amplitude $$0.06 \mathrm{~m}$$ and time period $$3.14 \mathrm{~s}$$. The maximum velocity of the particle is _________ $$\mathrm{cm} / \mathrm{s}$$.
Răspuns
12
24
Three infinitely long charged thin sheets are placed as shown in figure. The magnitude of electric field at the point $$P$$ is $$\frac{x \sigma}{\epsilon_0}$$. The value of $$x$$ is _________ (all quantities are measured in SI units).

Răspuns
2
25
Radius of a certain orbit of hydrogen atom is 8.48 $$\mathop A\limits^o$$. If energy of electron in this orbit is $$E / x$$. then $$x=$$ ________ (Given $$\mathrm{a}_0=0.529$$ $$\mathop A\limits^o$$, $$E=$$ energy of electron in ground state).
Răspuns
16
26
For three vectors $$\vec{A}=(-x \hat{i}-6 \hat{j}-2 \hat{k}), \vec{B}=(-\hat{i}+4 \hat{j}+3 \hat{k})$$ and $$\vec{C}=(-8 \hat{i}-\hat{j}+3 \hat{k})$$, if $$\vec{A} \cdot(\vec{B} \times \vec{C})=0$$, then value of $$x$$ is ________.
Răspuns
4
27
The refractive index of prism is $$\mu=\sqrt{3}$$ and the ratio of the angle of minimum deviation to the angle of prism is one. The value of angle of prism is _________$$^\circ$$.
Răspuns
60
28
A wire of resistance $$R$$ and radius $$r$$ is stretched till its radius became $$r / 2$$. If new resistance of the stretched wire is $$x ~R$$, then value of $$x$$ is ________.
Răspuns
16
29
When a $$d c$$ voltage of $$100 \mathrm{~V}$$ is applied to an inductor, a $$d c$$ current of $$5 \mathrm{~A}$$ flows through it. When an ac voltage of $$200 \mathrm{~V}$$ peak value is connected to inductor, its inductive reactance is found to be $$20 \sqrt{3} \Omega$$. The power dissipated in the circuit is _________ W.
Răspuns
250
30
A circular coil having 200 turns, $$2.5 \times 10^{-4} \mathrm{~m}^2$$ area and carrying $$100 \mu \mathrm{A}$$ current is placed in a uniform magnetic field of $$1 \mathrm{~T}$$. Initially the magnetic dipole moment $$(\vec{M})$$ was directed along $$\vec{B}$$. Amount of work, required to rotate the coil through $$90^{\circ}$$ from its initial orientation such that $$\vec{M}$$ becomes perpendicular to $$\vec{B}$$, is ________ $$\mu$$J.
Răspuns
5