Other Physics · JEE Main previous year questions

1. A.$\Delta Q_A>\Delta Q_B$; $\Delta U_A>\Delta U_B$
2. B.$\Delta Q_A<\Delta Q_B$; $\Delta U_A<\Delta U_B$
3. C.$\Delta Q_A>\Delta Q_B$; $\Delta U_A=\Delta U_B$
4. D.$\Delta Q_A=\Delta Q_B$; $\Delta U_A=\Delta U_B$

1. A.Repulsive and equal to ${\mu }_0{I}_1{I}_2/4\pi$
2. B.Attractive and equal to ${\mu }_0{I}_1{I}_2/3\pi$
3. C.Repulsive and equal to ${\mu }_0{I}_1{I}_2/2\pi$
4. D.Zero

Two coils 'P' and 'Q' are separated by some distance. When a current of 3 A flows through coil 'P', a magnetic flux of $10^{-3}\mathrm{Wb}$ passes through 'Q'. No current is passed through 'Q'. When no current passes through 'P' and a current of 2 A passes through 'Q', the flux through 'P' is :-

1. A.$3.67\times 10^{-4}\mathrm{Wb}$
2. B.$3.67\times 10^{-3}\mathrm{Wb}$
3. C.$6.67\times 10^{-4}\mathrm{Wb}$
4. D.$6.67\times 10^{-3}\mathrm{Wb}$

The position of a particle as a function of time t, is given by $x(t)=at+b{t}^2-c{t}^3$ where a, b and c are constants. When the particle attains zero acceleration, then its velocity will be :

1. A.$a+\frac{b^2}{c}$
2. B.$a+\frac{b^2}{4c}$
3. C.$a+\frac{b^2}{3c}$
4. D.$a+\frac{b^2}{2c}$

The position vector of a particle changes with time according to the relation $\vec{r}(t)=15t^2\hat{i}+(4-20t^2)\hat{j}$ What is the magnitude of the acceleration at t = 1 ?

1. A.50
2. B.25
3. C.40
4. D.100

Young's moduli of two wires A and B are in the ratio 7 : 4. Wire A is 2 m long and has radius R. Wire B is 1.5 m long and has radius 2 mm. If the two wires stretch by the same length for a given load, then the value of R is close to :-

1. A.1.7 mm
2. B.1.9 mm
3. C.1.3 mm
4. D.1.5 mm

A rocket has to be launched from earth in such a way that it never returns. If E is the minimum energy delivered by the rocket launcher, what should be the minimum energy that the launcher should have if the same rocket is to be launched from the surface of the moon ? Assume that the density of the earth and the moon are equal and that the earth's volume is 64 times the volume of the moon :-

1. A.E/32
2. B.E/16
3. C.E/4
4. D.E/64

Let $|{\vec{A}}_1|=3$, $|{\vec{A}}_2|=5$ and $|{\vec{A}}_1+{\vec{A}}_2|=5$. The value of $(2{\vec{A}}_1+3{\vec{A}}_2)\cdot (3{\vec{A}}_1-2{\vec{A}}_2)$ is :-

1. A.−118.5
2. B.−112.5
3. C.−99.5
4. D.−106.5

Two electric bulbs, rated at $(25\mathrm{W},220\mathrm{V})$ and $(100\mathrm{W},220\mathrm{V})$, are connected in series across a $220\mathrm{V}$ voltage source. If the $25\mathrm{W}$ and $100\mathrm{W}$ bulbs draw powers $P_1$ and $P_2$ respectively, then :

1. A.$P_1=4\mathrm{W},P_2=16\mathrm{W}$
2. B.$P_1=16\mathrm{W},P_2=4\mathrm{W}$
3. C.$P_1=9\mathrm{W},P_2=16\mathrm{W}$
4. D.$P_1=16\mathrm{W},P_2=9\mathrm{W}$

To double the covering range of a TV transmission tower, its height should be multiplied by :

1. A.4
2. B.2
3. C.$\sqrt{2}$
4. D.$\frac{1}{\sqrt{2}}$

When $100\text{ g}$ of a liquid A at $100^{\circ }\mathrm{C}$ is added to $50\text{ g}$ of a liquid B at temperature $75^{\circ }\mathrm{C}$, the temperature of the mixture becomes $90^{\circ }\mathrm{C}$. The temperature of the mixture, if $100\text{ g}$ of liquid A at $100^{\circ }\mathrm{C}$ is added to $50\text{ g}$ of liquid B at $50^{\circ }\mathrm{C}$, will be :

1. A.$60^{\circ }\mathrm{C}$
2. B.$70^{\circ }\mathrm{C}$
3. C.$85^{\circ }\mathrm{C}$
4. D.$80^{\circ }\mathrm{C}$

A thermometer graduated according to a linear scale reads a value $x_0$ when in contact with boiling water, and $x_0/3$ when in contact with ice. What is the temperature of an object in ${}^{\circ }\mathrm{C}$, if this thermometer in the contact with the object reads $x_0/2$ ?

1. A.60
2. B.35
3. C.25
4. D.40

In a process, temperature and volume of one mole of an ideal monoatomic gas are varied according to the relation $\mathrm{VT}=\mathrm{K}$, where K is a constant. In this process the temperature of the gas is increased by $\Delta \mathrm{T}$. The amount of heat absorbed by gas is (R is gas constant) :

1. A.$\frac{1}{2}\mathrm{KR}\Delta \mathrm{T}$
2. B.$\frac{1}{2}\mathrm{R}\Delta \mathrm{T}$
3. C.$\frac{3}{2}\mathrm{R}\Delta \mathrm{T}$
4. D.$\frac{2K}{3}\Delta \mathrm{T}$

1. A.$(1+9\sin (2\pi \times 10^4\text{ t}))\sin (2.5\pi \times 10^5\text{t})\text{ V}$
2. B.$(9+\sin (4\pi \times 10^4\text{ t}))\sin (5\pi \times 10^5\text{t})\text{ V}$
3. C.$(9+\sin (2\pi \times 10^4\text{ t}))\sin (2.5\pi \times 10^5\text{t})\text{ V}$
4. D.$(9+\sin (2.5\pi \times 10^4\text{ t}))\sin (2\pi \times 10^4\text{t})\text{ V}$

Let $\vec{A}=\left(\hat{i}+\hat{j}\right)$ and, $\vec{B}=\left(2\hat{i}-\hat{j}\right)$. The magnitude of a coplanar vector $\vec{C}$ such that $\vec{A}\cdot \vec{C}=\vec{B}\cdot \vec{C}=\vec{A}\cdot \vec{B}$, is given by :

1. A.$\sqrt{\frac{10}{9}}$
2. B.$\sqrt{\frac{5}{9}}$
3. C.$\sqrt{\frac{20}{9}}$
4. D.$\sqrt{\frac{9}{12}}$

Two particles of the same mass m are moving in circular orbits because of force, given by $F(r)=\frac{-16}{r}-r^3$ The first particle is at a distance $r=1$, and the second, at $r=4$. The best estimate for the ratio of kinetic energies of the first and the second particle is closest to :

1. A.$6\times 10^{-2}$
2. B.$3\times 10^{-3}$
3. C.$10^{-1}$
4. D.$6\times 10^2$

Two moles of helium are mixed with n moles of hydrogen. If $\frac{C_p}{Cv}=\frac{3}{2}$ for the mixture, then the value of n is :

1. A.1
2. B.3
3. C.2
4. D.3 / 2

Two identical conducting spheres A and B, carry equal charge. They are separated by a distance much larger than their diameters, and the force between them is F. A third identical conducting sphere, C, is uncharged. Sphere C is first touched to A, then to B, and then removed. As a result, the force between A and B would be equal to :

1. A.F
2. B.$\frac{3F}{4}$
3. C.$\frac{3F}{8}$
4. D.$\frac{F}{2}$

An automobile, travelling at $40\text{km/h}$, can be stopped at a distance of 40 m by applying brakes. If the same automobile is travelling at $80\text{km/h}$, the minimum stopping distance, in metres, is (assume no skidding) :

1. A.45 m
2. B.100 m
3. C.150 m
4. D.160 m

Take the mean distance of the moon and the sun from the earth to be $0.4\times 10^6\text{km}$ and $150\times 10^6\text{km}$ respectively. Their masses are $8\times 10^{22}\text{kg}$ and $2\times 10^{30}\text{kg}$ respectively. The radius of the earth is $6400\text{km}$. Let $\Delta F_1$ be the difference in the forces exerted by the moon at the nearest and farthest points on the earth and $\Delta F_2$ be the difference in the force exerted by the sun at the nearest and farthest points on the earth. Then, the number closest to $\frac{\Delta F_1}{\Delta F_2}$ is :

1. A.2
2. B.$10^{-2}$
3. C.0.6
4. D.6

A thin uniform tube is bent into a circle of radius $r$ in the vertical plane. Equal volumes of two immiscible liquids, whose densities are ${\rho }_1$ and ${\rho }_2$ (${\rho }_1>{\rho }_2$), fill half the circle. The angle $\theta$ between the radius vector passing through the common interface and the vertical is :

1. A.$\theta ={\tan }^{-1}\pi \left(\frac{{\rho }_1}{{\rho }_2}\right)$
2. B.$\theta ={\tan }^{-1}\frac{\pi }{2}\left(\frac{{\rho }_1}{{\rho }_2}\right)$
3. C.$\theta ={\tan }^{-1}\left(\frac{{\rho }_1-{\rho }_2}{{\rho }_1+{\rho }_2}\right)$
4. D.$\theta ={\tan }^{-1}\frac{\pi }{2}\left(\frac{{\rho }_1+{\rho }_2}{{\rho }_1-{\rho }_2}\right)$

The energy required to remove the electron from a singly ionized Helium atom is 2.2 times the energies required to remove an electron from Helium atom. The total energy required to ionize the Helium atom completely is :

1. A.$20eV$
2. B.$34eV$
3. C.$79eV$
4. D.$109eV$

1. A.$\tan \theta =\frac{1}{2}$
2. B.$\tan \theta =2$
3. C.$\tan \theta =4$
4. D.$\tan \theta =\frac{1}{4}$

The number of amplitude modulted broadcast stations that can be accomodated in a $300kHz$ band width for the highest modulating frequency $15kHz$ will be :

1. A.20
2. B.15
3. C.10
4. D.8

1. A.
2. B.
3. C.
4. D.