List of top Physics Questions asked in JEE Main

Potential energy as a function of r is given by $U = \frac{A}{r^{10}}-\frac{B}{r^5}$, where $r$ is the interatomic distance, A and B are positive constants. The equilibrium distance between the two atoms will be:

A long straight wire with a circular cross-section having radius R, is carrying a steady current I. The current I is uniformly distributed across this cross-section. Then the variation of magnetic field due to current I with distance r (r < R) from its centre

The cut-off voltage of the diodes (shown in figure) in forward bias is $0.6\; V$. The current through the resistor of $40$ $Ω$ is____ mA.

The equivalent capacitance between points A and B in below shown figure will be ______ μF.

A geyser heats water flowing at a rate of 2.0 kg per minute from 30°C to 70°C. If geyser operates on a gas burner, the rate of combustion of fuel will be __________ g min^–1.
[Heat of combustion = 8 × 10³ Jg^–1, Specific heat of water = 4.2 Jg^–1°C^–1]

Same gas is filled in two vessels of the same volume at the same temperature. If the ratio of the number of molecules is 1 : 4, then

A. The r.m.s. velocity of gas molecules in two vessels will be the same.

B. The ratio of pressure in these vessels will be 1 : 4.

C. The ratio of pressure will be 1 : 1.

D. The r.m.s. velocity of gas molecules in two vessels will be in the ratio of 1 : 4.

Choose the correct answer from the options given below.

Resistances are connected in a meter bridge circuit as shown in the figure. The balancing length l₁ is 40 cm. Now an unknown resistance x is connected in series with P and new balancing length is found to be 80 cm measured from the same end. Then the value of x will be ________ Ω.

An antenna is placed in a dielectric medium of dielectric constant $6.25$. If the maximum size of that antenna is $5.0$ $mm$, it can radiate a signal of minimum frequency of __________GHz. (Given $μr$ = $1$ for dielectric medium)

Read the following statements:

A. When small temperature difference between a liquid and its surrounding is doubled, the rate of loss of heat of the liquid becomes twice.

B. Two bodies P and Q having equal surface areas are maintained at temperature 10°C and 20°C. The thermal radiation emitted in a given time by P and Q are in the ratio 1 : 1.15.

C. A carnot Engine working between 100 K and 400 K has an efficiency of 75%.

D. When small temperature difference between a liquid and its surrounding is quadrupled, the rate of loss of heat of the liquid becomes twice.

Choose the correct answer from the options given below

The velocity of a small ball of mass ‘m’ and density $d_1$, when dropped in a container filled with glycerin, becomes constant after some time. If the density of glycerin is $d_2$, then the viscous force acting on the ball, will be

In the wave equation $y=05 \sin \frac{2 \pi}{\lambda}(400 t-x) m$ the velocity of the wave will be :

Given below are two statements:
Statement I: The average momentum of a molecule in a sample of an ideal gas depends on temperature.
Statement II: The rms speed of oxygen molecules in a gas is $v$ If the temperature is doubled and the oxygen molecules dissociate into oxygen atoms, the rms speed will become $2 v$ In the light of the above statements, choose the correct answer from the options given below:

In an experiment to find acceleration due to gravity (g) using simple pendulum, time period of 0.5 s is measured from time of 100 oscillations with a watch of 1 s resolution. If measured value of length is 10 cm known to 1 mm accuracy, the accuracy in the determination of g is found to be x %. The value of x is _________ .

In the given circuit, the magnitude of V_L and V_C are twice that of V_R. Given that f = 50 Hz, the inductance of the coil is $\frac{1}{(K\pi)} \text{mH}$. The value of K is ________.

In a Young’s double slit experiment, an angular width of the fringe is 0.35° on a screen placed at
2 m away for particular wavelength of 450 nm. The angular width of the fringe, when whole system is immersed in a medium of refractive index $\frac{7}{5}$, is $\frac{1}{\alpha}$. The value of $\alpha$ is _________.

A zener of breakdown voltage V_Z = 8 V and maximum Zener current, I_ZM = 10 mA is subjected to an input voltage V_i = 10 V with series resistance R = 100 Ω. In the given circuit R_L represents the variable load resistance. The ratio of maximum and minimum value of R_L is __________.

At a certain temperature, the degrees of freedom per molecule for gas is 8. The gas performs 150 J of work when it expands under constant pressure. The amount of heat absorbed by the gas will be ______ J.

A string of area of cross-section $4mm^2$ and length $0.5 m$ is connected with a rigid body of mass $2 kg$. The body is rotated in a vertical circular path of radius $0.5 m$. The body acquires a speed of $5 m/s$ at the bottom of the circular path. Strain produced in the string when the body is at the bottom of the circle is ______$×10^{–5}$.

(use young’s modulus $10^{11} N/m^2$ and $g = 10 m/s^2$)

An object O is placed at a distance of 100 cm in front of a concave mirror of radius of curvature 200 cm as shown in the figure. The object starts moving towards the mirror at a speed 2 cm/s. The position of the image from the mirror after 10 s will be at ____ cm.

An electrical bulb rated 220 V, 100 W, is connected in series with another bulb rated 220 V, 60 W. If the voltage across combination is 220 V, the power consumed by the 100 W bulb will be about ____ W.

For the given circuit the current through battery of 6 V just after closing the switch S will be _____ A.

A balloon has mass of 10 g in air The air escapes from the balloon at a uniform rate with velocity 4.5 cm/s If the balloon shrinks in 5 s completely Then, the average force acting on that balloon will be (in dyne)

A Carnot engine has efficiency of $50 \%$ .If the temperature of sink is reduced by $40^{\circ} C$, its efficiency increases by $30 \%$ .The temperature of the source will be :

In an experiment with a convex lens, the plot of the image distance (ν′) against the object distance (μ′) measured from the focus gives a curve ν′μ′ = 225. If all the distances are measured in cm. The magnitude of the focal length of the lens is _______ cm.

The potential energy of a particle of mass $4 kg$ in motion along the x-axis is given by $U = 4(1- cos 4x) J$. The time period of the particle for small oscillation $(sin θ ≃ θ)$ is $(\frac{π}{K})$ s. The value of $K$ is ..........