JEE MAIN - Physics (2023 - 6th April Morning Shift)

1
A particle is moving with constant speed in a circular path. When the particle turns by an angle $$90^{\circ}$$, the ratio of instantaneous velocity to its average velocity is $$\pi: x \sqrt{2}$$. The value of $$x$$ will be -
Respondre
(D)
2
2
The induced emf can be produced in a coil by

A. moving the coil with uniform speed inside uniform magnetic field

B. moving the coil with non uniform speed inside uniform magnetic field

C. rotating the coil inside the uniform magnetic field

D. changing the area of the coil inside the uniform magnetic field

Choose the correct answer from the options given below:
Respondre
(B)
C and D only
3
Name the logic gate equivalent to the diagram attached

Respondre
(A)
NOR
4
Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R

Assertion A : When a body is projected at an angle $$45^{\circ}$$, it's range is maximum.

Reason R : For maximum range, the value of $$\sin 2 \theta$$ should be equal to one.

In the light of the above statements, choose the correct answer from the options given below:
Respondre
(A)
Both $$\mathbf{A}$$ and $$\mathbf{R}$$ are correct and $$\mathbf{R}$$ is the correct explanation of $$\mathbf{A}$$
5
A source supplies heat to a system at the rate of $$1000 \mathrm{~W}$$. If the system performs work at a rate of $$200 \mathrm{~W}$$. The rate at which internal energy of the system increases is
Respondre
(D)
800 W
6
A small ball of mass $$\mathrm{M}$$ and density $$\rho$$ is dropped in a viscous liquid of density $$\rho_{0}$$. After some time, the ball falls with a constant velocity. What is the viscous force on the ball ?
Respondre
(A)
$$\mathrm{F}=\mathrm{Mg}\left(1-\frac{\rho_{\mathrm{O}}}{\rho}\right)$$
7
A small block of mass $$100 \mathrm{~g}$$ is tied to a spring of spring constant $$7.5 \mathrm{~N} / \mathrm{m}$$ and length $$20 \mathrm{~cm}$$. The other end of spring is fixed at a particular point A. If the block moves in a circular path on a smooth horizontal surface with constant angular velocity $$5 ~\mathrm{rad} / \mathrm{s}$$ about point $$\mathrm{A}$$, then tension in the spring is -
Respondre
(C)
0.75 N
8
Given below are two statements : one is labelled as Assertion $$\mathbf{A}$$ and the other is labelled as Reason $$\mathbf{R}$$.

Assertion A : Earth has atmosphere whereas moon doesn't have any atmosphere.

Reason R : The escape velocity on moon is very small as compared to that on earth.

In the light of the above statements, choose the correct answer from the options given below:
Respondre
(C)
Both $$\mathbf{A}$$ and $$\mathbf{R}$$ are correct and $$\mathbf{R}$$ is the correct explanation of $$\mathbf{A}$$
9
The kinetic energy of an electron, $$\alpha$$-particle and a proton are given as $$4 \mathrm{~K}, 2 \mathrm{~K}$$ and $$\mathrm{K}$$ respectively. The de-Broglie wavelength associated with electron $$(\lambda \mathrm{e}), \alpha$$-particle $$((\lambda \alpha)$$ and the proton $$(\lambda p)$$ are as follows:
Respondre
(A)
$$\lambda \alpha<\lambda p<\lambda e$$
10
A monochromatic light wave with wavelength $$\lambda_{1}$$ and frequency $$v_{1}$$ in air enters another medium. If the angle of incidence and angle of refraction at the interface are $$45^{\circ}$$ and $$30^{\circ}$$ respectively, then the wavelength $$\lambda_{2}$$ and frequency $$v_{2}$$ of the refracted wave are:
Respondre
(D)
$$\lambda_{2}=\frac{1}{\sqrt{2}} \lambda_{1}, v_{2}=v_{1}$$
11
A long straight wire of circular cross-section (radius a) is carrying steady current I. The current I is uniformly distributed across this cross-section. The magnetic field is
Respondre
(C)
directly proportional to $$r$$ in the region $$r < a$$ and inversely proportional to $$r$$ in the region $$r > a$$
12
A planet has double the mass of the earth. Its average density is equal to that of the earth. An object weighing $$\mathrm{W}$$ on earth will weigh on that planet:
Respondre
(D)
$$2^{1 / 3} \mathrm{~W}$$
13
A mass $$m$$ is attached to two strings as shown in figure. The spring constants of two springs are $$\mathrm{K}_{1}$$ and $$\mathrm{K}_{2}$$. For the frictionless surface, the time period of oscillation of mass $$m$$ is :

Respondre
(A)
$$2\pi \sqrt {{m \over {{K_1} + {K_2}}}} $$
14
Two resistances are given as $$\mathrm{R}_{1}=(10 \pm 0.5) \Omega$$ and $$\mathrm{R}_{2}=(15 \pm 0.5) \Omega$$. The percentage error in the measurement of equivalent resistance when they are connected in parallel is -
Respondre
(C)
4.33
15
For the plane electromagnetic wave given by $$E=E_{0} \sin (\omega t-k x)$$ and $$B=B_{0} \sin (\omega t-k x)$$, the ratio of average electric energy density to average magnetic energy density is
Respondre
(A)
1
16
The resistivity $$(\rho)$$ of semiconductor varies with temperature. Which of the following curve represents the correct behaviour :
Respondre
(D)
17
The energy levels of an hydrogen atom are shown below. The transition corresponding to emission of shortest wavelength is :

Respondre
(D)
D
18
The number of air molecules per cm$$^3$$ increased from $$3\times10^{19}$$ to $$12\times10^{19}$$. The ratio of collision frequency of air molecules before and after the increase in number respectively is:
Respondre
(B)
0.25
19
For a uniformly charged thin spherical shell, the electric potential (V) radially away from the centre (O) of shell can be graphically represented as -

Respondre
(A)
20
The radius of fifth orbit of the $$\mathrm{Li}^{++}$$ is __________ $$\times 10^{-12} \mathrm{~m}$$.

Take: radius of hydrogen atom $$ = 0.51\,\mathop A\limits^o $$
Respondre
425
21
Two identical solid spheres each of mass $$2 \mathrm{~kg}$$ and radii $$10 \mathrm{~cm}$$ are fixed at the ends of a light rod. The separation between the centres of the spheres is $$40 \mathrm{~cm}$$. The moment of inertia of the system about an axis perpendicular to the rod passing through its middle point is __________ $$\times 10^{-3} \mathrm{~kg}~\mathrm{m}^{2}$$
Respondre
176
22
A steel rod has a radius of $$20 \mathrm{~mm}$$ and a length of $$2.0 \mathrm{~m}$$. A force of $$62.8 ~\mathrm{kN}$$ stretches it along its length. Young's modulus of steel is $$2.0 \times 10^{11} \mathrm{~N} / \mathrm{m}^{2}$$. The longitudinal strain produced in the wire is _____________ $$\times 10^{-5}$$
Respondre
25
23
Two identical circular wires of radius $$20 \mathrm{~cm}$$ and carrying current $$\sqrt{2} \mathrm{~A}$$ are placed in perpendicular planes as shown in figure. The net magnetic field at the centre of the circular wires is __________ $$\times 10^{-8} \mathrm{~T}$$.

(Take $$\pi=3.14$$)
Respondre
628
24
A pole is vertically submerged in swimming pool, such that it gives a length of shadow $$2.15 \mathrm{~m}$$ within water when sunlight is incident at angle of $$30^{\circ}$$ with the surface of water. If swimming pool is filled to a height of $$1.5 \mathrm{~m}$$, then the height of the pole above the water surface in centimeters is $$\left(n_{w}=4 / 3\right)$$ ____________.
Respondre
50
25
A particle of mass $$10 \mathrm{~g}$$ moves in a straight line with retardation $$2 x$$, where $$x$$ is the displacement in SI units. Its loss of kinetic energy for above displacement is $$\left(\frac{10}{x}\right)^{-n}$$ J. The value of $$\mathrm{n}$$ will be __________
Respondre
2
26
The length of a metallic wire is increased by $$20 \%$$ and its area of cross section is reduced by $$4 \%$$. The percentage change in resistance of the metallic wire is __________.
Respondre
25
27
A parallel plate capacitor with plate area $$\mathrm{A}$$ and plate separation $$\mathrm{d}$$ is filled with a dielectric material of dielectric constant $$K=4$$. The thickness of the dielectric material is $$x$$, where $$x < d$$.

Let $$\mathrm{C}_{1}$$ and $$\mathrm{C}_{2}$$ be the capacitance of the system for $$\chi=\frac{1}{3} d$$ and $$\mathcal{X}=\frac{2 d}{3}$$, respectively. If $$\mathrm{C}_{1}=2 \mu \mathrm{F}$$ the value of $$\mathrm{C}_{2}$$ is __________ $$\mu \mathrm{F}$$
Respondre
3
28
An ideal transformer with purely resistive load operates at $$12 ~\mathrm{kV}$$ on the primary side. It supplies electrical energy to a number of nearby houses at $$120 \mathrm{~V}$$. The average rate of energy consumption in the houses served by the transformer is 60 $$\mathrm{kW}$$. The value of resistive load $$(\mathrm{Rs})$$ required in the secondary circuit will be ___________ $$\mathrm{m} \Omega$$.
Respondre
240