List of top Physics Questions asked in JEE Main

An electrical power line, having a total resistance of $2\Omega,$ delivers $1\, kW$ at $220\, V$. The efficiency of the transmission line is approximately:

Model a torch battery of length $l$ to be made up of a thin cylindrical bar of radius $'a'$ and a concentric thin cylindrical shell of radius $'b'$ filled in between with an electrolyte of resistivity $\rho$ (see figure). If the battery is connected to a resistance of value $R ,$ the maximum Joule heating in $R$ will take place for :

In a building there are $15$ bulbs of $45\, W, 15$ bulbs of $100\, W$, $15$ small fans of $10\, W$ and $2$ heaters of $1\, kW$. The voltage of electric main is $220\, V$. The minimum fuse capacity (rated value) of the building will be:

A galvanometer of resistance $G$ is converted into a voltmeter of range $0-1 V$ by connecting a resistance $R _{1}$ in series with it. The additional resistance that should be connected in series with $R _{1}$ to increase the range of the voltmeter to $-2 V$ will be :

Consider a sphere of radius $R$ which carries a uniform charge density $\rho$. If a sphere of radius $\frac{R}{2}$ Ls carved out of it, as shown, the ratio $\frac{\left|\overrightarrow{E_{A}}\right|}{\left|\overrightarrow{E_{B}}\right|}$ of magnitude of electric field $\overrightarrow{E_{A}}$ and $\overrightarrow{E}_{B}$ respectively, at points A and B due to the remaining portion is :

A vessel of depth $2\,h$ is half filled with a liquid of refractive index $2\sqrt{2}$ and the upper half with another liquid of refractive index $\sqrt{2}$ The liquids are immiscible. The apparent depth of the inner surface of the bottom of vessel will be :

A thermodynamic cycle $xyzx$ is shown on a $V-T$ diagram. The $P-V$ diagram that best describes this cycle is : (Diagrams are schematic and not to scale)

In a radioactive material, fraction of active material remaining after time $t$ is $9 / 16 .$ The fraction that was remaining after $t / 2$ is :

The coordinates of centre of mass of a uniform flag shaped lamina (thin flat plate) of mass $4\, kg$. (The coordinates of the same are shown in figure) are :

Three solid spheres each of mass $m$ and diameter $d$ are stuck together such that the lines connecting the centres form an equilateral triangle of side of length $d$. The ratio $I_0/I_A$ of moment of inertia $I_0$ of the system about an axis passing the centroid and about center of any of the spheres $I_A$ and perpendicular to the plane of the triangle 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 $(10 \hat{ i }+4 \hat{ j }) ms ^{-2} .$ At time $t$, its coordinates are (20 $\left. m , y _{0} m \right)$. The values of $t$ and $y _{0}$, are respectively

In finding the electric field using Gauss law the formula $\left|\overrightarrow{E}\right|= \frac{q_{enc}}{\epsilon_{0}\left|A\right|}$ is applicable. In the formula $\epsilon_{0}$ is permittivity of free space, $A$ is the area of Gaussian surface and $ q_{enc}$ is charge enclosed by the Gaussian surface. This equation can be used in which of the following situation ?

A particle of charge $q$ and mass $m$ is subjected to an electric field $E = E _{0}\left(1- ax ^{2}\right)$ in the $x$ -direction, where a and $E_{0}$ are constants. Initially the particle was at rest at $x=0$. Other than the initial position the kinetic energy of the particle becomes zero when the distance of the particle from the origin is :

The aperture diameter of a telescope is 5 m. The separation between the moon and the ear this $4 \times 10^5$ km. With light of wavelength of 5500 $?$, the minimum separation between objects on the surface of moon, so that they are just resolved, is close to :

A cube of metal is subjected to a hydrostatic pressure of $4 \,GPa$. The percentage change in the length of the side of the cube is close to (Given bulk modulus of metal, $\left. B =8 \times 10^{10} Pa \right)$

The quantities $x=\frac{1}{\sqrt{\mu_{0} \epsilon_{0}}}, y=\frac{E}{B}$ and $z =\frac{1}{ CR }$ are defined where C - capacitance R - Resistance, l - length, E - Electric field, B - magnetic field and $\epsilon_{0}, \mu_{0},$ - free space permittivity and permeability respectively. Then :

Two particles of equal mass m have respective initial velocities $u\hat{i}$ and $u\left(\frac{\hat{i}+\hat{j}}{2}\right).$ They collide completely inelastically. The energy lost in the process is :

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

A small spherical droplet of density $d$ is floating exactly half immersed in a liquid of density $\rho$ and surface tension $T$. The radius of the droplet is (take note that the surface tension applies an upward force on the droplet):

A 60 HP electric motor lifts an elevator having a maximum total load capacity of 2000 kg. If the frictional force on the elevator is 4000 N, the speed of the elevator at full load is close to : ($1 \,HP = 746 \,W, \,g = 10\, ms^{-2}$ )

Planet $A$ has mass $M$ and radius $R$. Planet $B$ has half the mass and half the radius of Planet $A$. If the escape velocities from the Planets $A$ and $B$ are $v_A$ and $v_B$, respectively, then $\frac{v_{A}}{v_{B}}=\frac{n}{4}$. The value of $n$ is :

A screw gauge has $50$ divisions on its circular scale. The circular scale is $4 $ units ahead of the pitch scale marking, prior to use. Upon one complete rotation of the circular scale, a displacement of $0.5\, mm$ is noticed on the pitch scale. The nature of zero error involved, and the least count of the screw gauge, are respectively :

Amount of solar energy received on the earth's surface per unit area per unit time is defined a solar constant. Dimension of solar constant is:

If momentum $ (P)$, area $(A)$ and time $(T)$ are taken to be the fundamental quantities then the dimensional formula for energy is :

A quantity $x$ is given by $(IFv^2 / WL^{4})$ in terms of moment of inertia $I, $ force $ F$, velocity $v ,$ work $W$ and Length $L$. The dimensional formula for $x$ is same as that of :