JEE MAIN - Physics (2023 - 25th January Morning Shift)

1
A parallel plate capacitor has plate area 40 cm$$^2$$ and plates separation 2 mm. The space between the plates is filled with a dielectric medium of a thickness 1 mm and dielectric constant 5. The capacitance of the system is :
Jawab
(D)
$$\mathrm{\frac{10}{3}\varepsilon_0~F}$$

Match List I with List II

	List I		List II
A.	Surface tension	I.	$$\mathrm{kg~m^{-1}~s^{-1}}$$
B.	Pressure	II.	$$\mathrm{kg~ms^{-1}}$$
C.	Viscosity	III.	$$\mathrm{kg~m^{-1}~s^{-2}}$$
D.	Impulse	IV.	$$\mathrm{kg~s^{-2}}$$

Choose the correct answer from the options given below :

Jawab

(A)

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

3
The root mean square velocity of molecules of gas is
Jawab
(D)
Proportional to square root of temperature ($$\sqrt T$$)
4
Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R

Assertion A : Photodiodes are used in forward bias usually for measuring the light intensity.

Reason R : For a p-n junction diode, at applied voltage V the current in the forward bias is more than the current in the reverse bias for $$\mathrm{|{V_z}| > \pm v \ge |{v_0}|}$$ where $$\mathrm{v_0}$$ is the threshold voltage and $$\mathrm{V_z}$$ is the breakdown voltage.

In the light of the above statements, choose the correct answer from the options given below
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(D)
A is false but R is true

Match List I with List II

		List II (Magnitude of Magnetic Field at point O)
A.	I.	$${B_0} = {{{\mu _0}I} \over {4\pi r}}[\pi + 2]$$
B.	II.	$${B_0} = {{{\mu _0}} \over {4 }}{I \over r}$$
C.	III.	$${B_0} = {{{\mu _0}I} \over {2\pi r}}[\pi - 1]$$
D.	IV.	$${B_0} = {{{\mu _0}I} \over {4\pi r}}[\pi + 1]$$

Choose the correct answer from the options given below :

Jawab

(C)

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

6
In Young's double slits experiment, the position of 5$$\mathrm{^{th}}$$ bright fringe from the central maximum is 5 cm. The distance between slits and screen is 1 m and wavelength of used monochromatic light is 600 nm. The separation between the slits is :
Jawab
(A)
60 $$\mu$$m
7
T is the time period of simple pendulum on the earth's surface. Its time period becomes $$x$$ T when taken to a height R (equal to earth's radius) above the earth's surface. Then, the value of $$x$$ will be :
Jawab
(C)
2
8
Assume that the earth is a solid sphere of uniform density and a tunnel is dug along its diameter throughout the earth. It is found that when a particle is released in this tunnel, it executes a simple harmonic motion. The mass of the particle is 100 g. The time period of the motion of the particle will be (approximately)

(Take g = 10 m s$$^{-2}$$ , radius of earth = 6400 km)
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(B)
1 hour 24 minutes
9
A car travels a distance of '$$x$$' with speed $$v_1$$ and then same distance '$$x$$' with speed $$v_2$$ in the same direction. The average speed of the car is :
Jawab
(B)
$${{2{v_1}{v_2}} \over {{v_1} + {v_2}}}$$
10
Electron beam used in an electron microscope, when accelerated by a voltage of 20 kV, has a de-Broglie wavelength of $$\lambda_0$$. IF the voltage is increased to 40 kV, then the de-Broglie wavelength associated with the electron beam would be :
Jawab
(C)
$$\frac{\lambda_0}{\sqrt2}$$
11
A uniform metallic wire carries a current 2 A, when 3.4 V battery is connected across it. The mass of uniform metallic wire is 8.92 $$\times$$ 10$$^{-3}$$ kg, density is 8.92 $$\times$$ 10$$^{3}$$ kg/m$$^3$$ and resistivity is 1.7 $$\times$$ 10$$^{-8}~\Omega$$-$$\mathrm{m}$$. The length of wire is :
Jawab
(D)
$$l=10$$ m
12
A solenoid of 1200 turns is wound uniformly in a single layer on a glass tube 2 m long and 0.2 m in diameter. The magnetic intensity at the center of the solenoid when a current of 2 A flows through it is :
Jawab
(C)
$$\mathrm{1.2\times10^{3}~A~m^{-1}}$$
13
An electromagnetic wave is transporting energy in the negative $$z$$ direction. At a certain point and certain time the direction of electric field of the wave is along positive $$y$$ direction. What will be the direction of the magnetic field of the wave at that point and instant?
Jawab
(C)
Positive direction of $$x$$
14
An object of mass 8 kg is hanging from one end of a uniform rod CD of mass 2 kg and length 1 m pivoted at its end C on a vertical wall as shown in figure. It is supported by a cable AB such that the system is in equilibrium. The tension in the cable is (Take g = 10 m/s$$^2$$)

Jawab
(D)
300 N
15
In an LC oscillator, if values of inductance and capacitance become twice and eight times, respectively, then the resonant frequency of oscillator becomes $$x$$ times its initial resonant frequency $$\omega_0$$. The value of $$x$$ is :
Jawab
(A)
1/4
16
A car is moving with a constant speed of 20 m/s in a circular horizontal track of radius 40 m. A bob is suspended from the roof of the car by a massless string. The angle made by the string with the vertical will be : (Take g = 10 m/s$$^2$$)
Jawab
(C)
$$\frac{\pi}{4}$$
17
If $$\overrightarrow P = 3\widehat i + \sqrt 3 \widehat j + 2\widehat k$$ and $$\overrightarrow Q = 4\widehat i + \sqrt 3 \widehat j + 2.5\widehat k$$ then, the unit vector in the direction of $$\overrightarrow P \times \overrightarrow Q $$ is $${1 \over x}\left( {\sqrt 3 \widehat i + \widehat j - 2\sqrt 3 \widehat k} \right)$$. The value of $$x$$ is _________.
Jawab
4
18
$$\mathrm{I_{CM}}$$ is the moment of inertia of a circular disc about an axis (CM) passing through its center and perpendicular to the plane of disc. $$\mathrm{I_{AB}}$$ is it's moment of inertia about an axis AB perpendicular to plane and parallel to axis CM at a distance $$\frac{2}{3}$$R from center. Where R is the radius of the disc. The ratio of $$\mathrm{I_{AB}}$$ and $$\mathrm{I_{CM}}$$ is $$x:9$$. The value of $$x$$ is _____________.

Jawab
17
19
An object of mass 'm' initially at rest on a smooth horizontal plane starts moving under the action of force F = 2N. In the process of its linear motion, the angle $$\theta$$ (as shown in figure) between the direction of force and horizontal varies as $$\theta=\mathrm{k}x$$, where k is a constant and $$x$$ is the distance covered by the object from its initial position. The expression of kinetic energy of the object will be $$E = {n \over k}\sin \theta $$. The value of n is ___________.

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2
20
A ray of light is incident from air on a glass plate having thickness $$\sqrt3$$ cm and refractive index $$\sqrt2$$. The angle of incidence of a ray is equal to the critical angle for glass-air interface. The lateral displacement of the ray when it passes through the plate is ____________ $$\times$$ 10$$^{-2}$$ cm. (given $$\sin 15^\circ = 0.26$$)
Jawab
52
21
The wavelength of the radiation emitted is $$\lambda_0$$ when an electron jumps from the second excited state to the first excited state of hydrogen atom. If the electron jumps from the third excited state to the second orbit of the hydrogen atom, the wavelength of the radiation emitted will $$\frac{20}{x}\lambda_0$$. The value of $$x$$ is _____________.
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27
22
The distance between two consecutive points with phase difference of 60$$^\circ$$ in a wave of frequency 500 Hz is 6.0 m. The velocity with which wave is travelling is __________ km/s
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18
23
As shown in the figure, in an experiment to determine Young's modulus of a wire, the extension-load curve is plotted. The curve is a straight line passing through the origin and makes an angle of 45$$^\circ$$ with the load axis. The length of wire is 62.8 cm and its diameter is 4 mm. The Young's modulus is found to be $$x\times10^4$$ Nm$$^{-2}$$. The value of $$x$$ is ___________.

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5
24
An LCR series circuit of capacitance 62.5 nF and resistance of 50 $$\Omega$$, is connected to an A.C. source of frequency 2.0 kHz. For maximum value of amplitude of current in circuit, the value of inductance is __________ mH.

(Take $$\pi^2=10$$)
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100
25
In the given circuit, the equivalent resistance between the terminal A and B is __________ $$\Omega$$.

Jawab
10
26
A uniform electric field of 10 N/C is created between two parallel charged plates (as shown in figure). An electron enters the field symmetrically between the plates with a kinetic energy 0.5 eV. The length of each plate is 10 cm. The angle ($$\theta$$) of deviation of the path of electron as it comes out of the field is ___________ (in degree).

Jawab
45